ANNUAL REPORT 2011 Tracking changes in the abundance of UK

ANNUAL REPORT 2011

Cover photograph of Orange-tip, Anthocharis cardamines. During a year in which the majority of butterflies emerged early Orange-tip led the way being recorded over three weeks earlier than the average since 1976 whilst also producing its highest index on record. Photograph by Peter Eeles.

The text, figures and pictures in this publication are the copyright of the Centre for Ecology & Hydrology and Conservation unless otherwise stated and may not be reproduced without permission.

This report should be cited as Botham, M.S., Brereton, T.M., Middlebrook, I., Randle, Z. & Roy, D.B. 2013. Butterfly Monitoring Scheme report for 2011. Centre for Ecology & Hydrology. REPORT CONTENTS

The UKBMS n About the UKBMS 1 n UKBMS objectives 1 n Contacts 1

BUTTERFLY ABUNDANCE IN 2011 n Survey methods 2 n Summary 2 n Family overview 10 n accounts 11

UKBMS NEWS n Online Data Entry for Transect Walker 40 n A new way of analysing UKBMS data 40

FEATURES n The Wider Countryside Butterfly Survey in 2011 41 n Magdalen Hill Down – restoring butterfly populations over the long-term 45

CONTACT DETAILS FOR LOCAL CO-ORDINATORS 49

REFERENCES 51

APPENDICES n Appendix I: Trends in UK BAP status species 52 n Appendix II: Vernacular & scientific names of UK butterfly species 53

ACKNOWLEDGEMENTS (back cover) UKBMS

About the UKBMS n To ensure a high level of quality assurance for Welcome to the seventh report of the United butterfly monitoring data by development and Kingdom Butterfly Monitoring Scheme (UKBMS). promotion of standards, and by applying rigorous data validation and verification procedures. Changes in the abundance of butterflies throughout the United Kingdom have been monitored using transects n To secure and manage butterfly monitoring data and since 1976. Over the past 36 years, the huge network of provide access to academia, governments, industry recorders (more than 5,000) has collectively made and the public. almost a quarter of a million weekly visits to almost 2,000 different sites, covering over half a million n To advance knowledge in butterfly ecology through kilometres and counting more than 17 million butterflies. interpretation of butterfly monitoring data.

The UKBMS is based on a well-established and n To provide scientific underpinning for solutions to enjoyable recording method and has produced important issues arising from habitat insights into almost all aspects of butterfly ecology. and climate change.

Butterflies are uniquely placed amongst British terrestrial n To provide a knowledge base, including indicators and other invertebrate groups to act as indicators of of change, for government policies addressing the state of the environment, allowing us to assess the environmental issues. impacts of habitat change, climate change and the progress of government policy initiatives such as the UK n To promote public awareness and understanding of Post-2010 Biodiversity Framework, National Biodiversity butterflies through communication of the results of Strategies and Action Plans, agri-environment schemes the scheme. and the condition of Sites of Special Scientific Interest (SSSIs). Not only are butterflies biologically suitable as Further information on the UKBMS can be found at indicator species, having rapid lifecycles and, in many www.ukbms.org cases, high sensitivity to environmental conditions, but the recording and monitoring volunteer networks and datasets built up by Butterfly Conservation (BC) and the Contacts Centre for Ecology & Hydrology (CEH) enable accurate assessment of their trends. For general enquiries: Ian Middlebrook, Butterfly Conservation, Manor Yard, The UKBMS is run as a partnership between BC and East Lulworth, , BH20 5QP. CEH. The scheme also benefits from the active Tel: 01929 400209 involvement of the National Trust (NT), the Royal email: [email protected] Society for the Protection of Birds (RSPB), the Forestry Commission and several wildlife trusts and local For data requests: authorities and is funded by a multi-agency consortium Dr David Roy, CEH, Maclean Building, Benson Lane, (see Acknowledgements on back cover). Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB. Tel 01491 692517 UKBMS Objectives email: [email protected]

The UKBMS mission is to assess the status and trends Dr Marc Botham, CEH, Maclean Building, Benson of UK butterfly populations for conservation, research Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, and quality of life. The objectives of the scheme are: OX10 8BB. Tel 01491 692517 n To maintain and develop a network of transect and email: [email protected] other monitored sites in order to assess and interpret changes in the abundance and status of UK Dr Tom Brereton, Butterfly Conservation, Manor Yard, butterflies. East Lulworth, Dorset, BH20 5QP. Tel: 01929 400209 n To encourage participation in scientific butterfly email: [email protected] monitoring by supporting volunteer recording networks.

1 BUTTERFLY ABUNDANCE IN 2011

Survey methods canopy species, Purple, White-letter and Brown Hairstreaks and the Purple Emperor, even though transects In the UKBMS, data on the population status of UK are generally not considered the ideal monitoring method butterflies is derived from a wide-scale programme of for them. However, they are included because ‘extreme’ site-based monitoring. The majority of sites are high or low years in the abundance of these species can be monitored by butterfly transects (Pollard & Yates 1993). determined from transect monitoring and because there The transect method, which was established in 1976, are a small number of transects and timed counts directed involves weekly butterfly counts along fixed routes specifically towards some of these species. through the season made under strict weather, recording area and time of day criteria. Weekly counts for each The Collated Index for each species is updated each year species are summed to generate annual abundance with the inclusion of additional monitoring data and indices. For sites with missing weekly counts, a therefore indices may differ to those presented in earlier statistical model (a Generalised Additive Model, reports. Similarly, the rank order used to show those years ‘GAM’) is used to impute the missing values and to in which butterflies fared better or worse compared to calculate the index (Rothery & Roy 2001). For a number other years, may be modified by these additional data of specialist species (especially the fritillaries) two (see Table 1). As in recent reports, we have produced a ‘reduced effort’ scientific methods, adult timed counts combined single index for all sites for each species rather (Warren et al. 1981) and larval web counts (Lewis & than separate indices for double-brooded species. We are Hurford 1997), are also used to monitor annual currently working on new analytical techniques that will abundance, especially in more remote parts of the UK. In enable us to calculate separate indices for those species both methods, systematic recording is made on single with more than one brood in a year and aim to present days in suitable weather (when UKBMS recording indices for different broods in the future. criteria are met), with the counts converted to a robust index that accounts for both the size of the colony and the time in the season when the count was made. Summary

HIGHLIGHTS Data from all past and present transects and timed counts/larval webs at monitored sites are combined each • For a third year in a row more than a thousand sites were monitored with the number of standard transects alone year to derive regional and national ‘Collated’ Indices approaching one thousand. Trends were assessed for 56 (CI) and to estimate trends over time. Because not all of the 59 regularly occurring UK species, which is two sites are monitored each year, a statistical model (log- more than ever before and includes two of our rarer linear regression) is needed to estimate missing values butterflies: Swallowtail and Glanville Fritillary. and to produce indices and trends. The model takes into • 2011 was a record breaking year for butterflies being on account the fact that, for a particular butterfly species, the wing early as a result of the exceptionally warm spring, with 22 species showing their earliest mean some years are better than others (a year effect), typically emergence dates* since monitoring began in 1976. due to the weather, and some sites support larger Several species including Orange-tip and Green populations than others (a site effect). The precision of Hairstreak were on the wing up to three weeks earlier on indices and trends is estimated by a further statistical average than in 2010. A further 10 species recorded their second earliest mean emergence dates*. technique called ‘bootstrapping’. • Spring species had a superb year with Orange-tip having its best year on record and a number of This is now the seventh year that data from a combined threatened species showing large annual increases: UKBMS dataset have been used to calculate trends in Pearl-bordered Fritillary and Duke of Burgundy did butterfly populations. In 2011 the number of UKBMS particularly well with abundance up by more than 50% sites on which butterfly numbers were recorded was more over 2010. than 1,000 for the third year running (966 transects and • After a superb start the season repeated the pattern of 127 larval web/timed counts). Figure 1 shows the UK 2007-2010 and fell away with cool and wet summer weather resulting in the majority of later summer species coverage of these sites in 2011, once again demonstrating having a poor year. As a result, it was a distinctly the immense commitment by volunteers. This enabled average year overall, ranking 18 in the 36–year series. Collated Indices to be calculated for 56 of the 59 regular • A number of species that had a superb year in 2010 species of butterfly in the UK. This includes two species showed large annual declines, including Marsh Fritillary, more than 2010, following the inclusion of Swallowtail Wood White, Common Blue and Brown Argus. and Glanville Fritillary which produced indices on five or • Of most concern, was the annual decrease of several more sites in 2011. In addition, for the first time we species in long-term decline. Both provide species accounts for all species recorded on and High Brown Fritillary produced their fourth lowest indices of the series. UKBMS sites in 2011, including some of our rarer species for which statistical analyses are not yet possible. As in *mean emergence dates were calculated as the mean of the first records across all sites a species was recorded at for each year previous years, trends were assessed for a number of

2 BUTTERFLY ABUNDANCE IN 2011

1200 Other methods Transects 1000

800

600

400

200

No. sites No. producing an index 0 1976 1981 1986 1991 1996 2001 2006 2011

Figure 1. Location of UKBMS sites

3 BUTTERFLY ABUNDANCE IN 2011

January received above average sunshine and below 600 30 2011 - no.

average rainfall over the month. Following the coldest 10-yr average - no. 500 25 December in more than 100 years temperatures were 2011 - sp closer to average, though a warm maximum of 14.5˚C 400 10-yr average - sp 20 was recorded at Pershore College (Worcestershire) on the 13th. Six species made an appearance, with Red 300 15

Admiral being the first, welcoming in the new year in 200 10 Cornwall on the 1st. Brimstone (Wiltshire) and Peacock (Isles of Scilly) followed a week later on the 8th and 9th 100 5 Average no. speciesrecorded Average

respectively, which were then followed by Small recorded no. butterflies Average 0 0 Tortoiseshell on the 18th, in three different counties April May June July August September (Cornwall, Dorset and Yorkshire) and Comma on the 19th (Yorkshire). Back down in Cornwall on the 20th, Figure 2. The average number of butterflies (on the left axis and assuming the Red Admiral on the 1st was probably an denoted by black solid and dashed lines) and average number of species (on the right hand axis and denoted by grey solid and individual that overwintered in the UK, the first migrant dashed lines) on transects each month in 2011 and averaged butterfly was recorded – Painted Lady. across the last 10 years.

Mild weather was a feature of February with the mean sunshine and a lot more cloud. Whilst it was dry and hot temperature across the UK 2˚C above average and a in East Anglia and one of the driest years on record in maximum of 16˚C recorded at Edenbridge (Kent) on the Essex and Kent, Scotland endured the wettest May on 24th. However, the weather was unsettled with spells of record. The maximum temperature of 25.4˚C was rain and cloud. Only one new species was recorded in recorded in Weybourne (Norfolk) on the 7th. Overall it February, Speckled Wood on the 13th (Isles of Scilly). was a good month, with butterfly abundance and March saw more settled weather arrive, and above diversity both higher than the May average over the last average temperature across the UK, with a maximum of 10 years. 20˚C on the 25th at Saunton Sands (Devon). It was also a very dry month across much of the UK, with East The warm spell continued into June, though it became Anglia recording the second driest March since 1910 much more unsettled with drought-ridden eastern and eastern recording less than 20% of the England getting some much needed rain. Temperatures normal rainfall for March. A further nine species were close to the long-term (since 1910) average, emerged throughout the month, including Orange-tip, though it was the coolest June in more than 10 years. Small, Large and Green-veined White, Green Butterfly abundance was up slightly over the 10-year Hairstreak, Small Copper, Holly Blue and Wall. The average (Figure 2). The highest June temperature, and in first Clouded Yellow of the year was also amongst these, fact the highest temperature of 2011, was recorded recorded in Devon on the 26th, the observation likely towards the month end in Gravesend (Kent) with a related to successful overwintering. scorching 33.1˚C. Things were shaping up to be one of the best years on record, and still seemed promising as April brought more fine weather with temperatures July started with generally fine, warm weather. nearly four degrees above the 1971-2000 average, However, patterns of the previous few years were making it the hottest April since records began. Central repeated and the weather became unsettled, with a low England clocked the warmest April in more than 350 pressure front driving prolonged and sometimes heavy years and daily maximum temperatures in south-east periods of rainfall. Mean temperatures were a degree England were up to 6˚C greater than the series average, cooler than the average, making it the coolest July since with the highest temperature of 27.8˚C recorded at 2000. The maximum temperature of 27.4˚C at Hartpury Wisley (Surrey) on the 23rd. Most of the UK was dry College (Gloucestershire) was considerably lower than with less than 10% of the normal rainfall for April and that achieved in June. So, once again, the weather there was plenty of sunshine. With great weather, it was became unfavourable at the peak time for butterflies in not surprising that both butterfly abundance and the UK. This was clearly evident as the number of diversity were well above average (Figure 2). A number butterflies recorded which, up until July, had been above of species including Green Hairstreak, Orange-tip and the average over the last 10 years, reversed Grizzled and Dingy Skippers were recorded earlier on substantially, although the number of species recorded transects than ever before. Across the month 30 species on transects was still greater than the average for July, were recorded on transects – five more than in 2010. because so many species had emerged earlier than usual The fabulous weather continued into May in south-east with the preceding warm spring/earl summer weather England but things started to change elsewhere and May (Figure 2). was generally a much more variable month with less

4 BUTTERFLY ABUNDANCE IN 2011

Although temperatures briefly breached the thirties with affected by the warm year-end, with spring flowers a maximum of 30.3˚C at Gravesend (Kent) on the 3rd, popping up in late autumn and spring moths being seen August was generally a cool month with disappointing around Christmas time. amounts of sunshine (only 75% of the normal amount at 2.2 this time of year). It was especially cool across Scotland and Northern Ireland (coolest since August 1993). 2.1

Rainfall levels were highly variable across the UK, with 2 over twice the average amount in certain areas (eastern 1.9 Scotland, north-east England, central southern England), and less rain than normal in other areas 1.8 (, west Midlands). The butterfly season, which 1.7 had promised to be one of the best on record, had truly 1.6 turned by this point and both the number of butterflies and number of species recorded on transects were well Index log Collated Composite 1.5 below the 10-year average. 1.4 1976 1981 1986 1991 1996 2001 2006 2011

It remained unsettled in the first three weeks of Figure 3. The combined Collated Index across all species for September, then, in the last week, unseasonably high each year of monitoring. 2010 is highlighted in red. temperatures were recorded including a monthly maximum of 29.2˚C at Cambridge (Cambridgeshire) 2011 overall was a particularly average year (Figure 3) and Sutton Bonington (Nottinghamshire) on the 30th. ranking 18th in the 36-year series (Table 1) with the Butterfly numbers on monitored sites picked up as a total number of butterflies counted lower than in the last consequence, and were close to the 10-year average two years. (Figure 2). These unseasonal temperatures continued into October with the average temperature up by 2˚C. A Table 1. UKBMS years ranked according to how good each year was relative to the others (1 = best, 36 = worst). maximum temperature of 29.9˚C at Gravesend (Kent) was the highest UK October temperature ever recorded. Year Rank Year Rank

However, not all of the UK was blessed with these 1976 5 1994 19 conditions: whilst rainfall was below average and 1977 35 1995 7 sunshine above average over East Anglia and south-east England, the reverse was true for Northern Ireland and 1978 28 1996 4 western Scotland, the former recording the dullest 1979 17 1997 2 October on record. The balmy, mild weather stayed with 1980 23 1998 24 us in November, with temperatures almost 3˚C above 1981 36 1999 29 the 1971-2000 average making it the second warmest 1982 6 2000 20

November in a hundred years. A maximum temperature 1983 16 2001 32 of 19.2˚C was recorded on the 13th at Tregarth 1984 3 2002 30 (Gwynedd) and northern Scotland endured the sunniest 21 2003 10 November on record. The year ended with another mild 1985 month, December 2011 being 0.6˚C above the 1971- 1986 26 2004 8 2000 average and the mildest since 2006 with a 1987 25 2005 9 maximum of 15.5˚C recorded at Fyvie Castle 1988 31 2006 14 (Aberdeenshire) on the 26th. Unlike the previous two 1989 15 2007 33 years where the year ended with cold, dry wintry 1990 11 2008 34 conditions, 2011 was characterised by rainfall – it rained 1991 12 2009 22 on most days, with more than 75% the normal amount. 1992 1 2010 13 In western and northern Scotland it was one of the wettest Decembers on record. There was limited 1993 27 2011 18 snowfall and few frosts. The last two years’ cold and dry Decembers resulted in good numbers of spring Despite the fantastic start for some of our threatened butterflies, as we had expected, given these are the specialist butterflies in the spring and early summer, the conditions widely regarded as beneficial to the composite measurement of habitat specialist species overwintering survival of many UK butterfly species. abundance was 11% lower than in 2010, ending a short 2011 was a stark contrast and we will have to wait to see run of two successive annual increases (Figure 4). what impact these conditions have on butterfly numbers Despite this small decline, numbers of habitat in 2012. Certainly a number of plants and moths were specialists overall were still pretty good and the long-

5 BUTTERFLY ABUNDANCE IN 2011

term trend of decline is now classed as stable. The Phenology 2011 results indicate that targeted conservation work has now halted the overall decline of specialist species, though Here we give a brief summary of butterfly phenology in problems still remain for individual species. Wider 2011 using the weighted mean date of counts as a countryside species, which until recently had been standardised measure (Botham et al 2008). Individual faring rather better than habitat specialists, declined species phenologies are presented in the species again with the 2011 index down by 9%. Given that a accounts. large number of our wider countryside species fly during July and August, when they can be extremely In 2010 the cool spring weather caused a number of abundant in good years (for example Meadow Brown, species that have been showing advances in their flight Gatekeeper and Small ), this is not so surprising. period over the long-term (e.g. Orange-tip and Green However, it further highlights the need to keep an eye on Hairstreak) to come out relatively late. 2011 started those species we pay less attention to because they are rather differently however, with unseasonably warm generally considered common and widespread. weather which caused many species to emerge early, Although it was not a fantastic year for migrant especially in comparison to 2010. For example, Orange- butterflies, abundance was up 39% over 2010. However, tip and Green Hairstreak were recorded around three the composite index was still below average, with the weeks earlier than in 2010. All but four species peaked group of butterflies showing a significant long-term earlier in their date of mean abundance than the average increase since 1976 (Figure 4). Painted Lady and since 1976. These advances were greater the earlier a Clouded Yellow numbers were still low after a slight species flies in the year (Figure 5). As the weather took a increase over 2010, whilst Red Admiral had a good year turn for the worse in mid-late summer, those species with large numbers being recorded towards the tail end emerging at this time of year showed only small of the season. advances or in fact came out a little later – Chalkhill Blue being the most extreme example, being almost two 3.5 weeks later than average. 3 20

Date of mean abundance 2011 2.5 10 2

0 1.5 -50 0 50 100 150 -10

log Collated Index Collated log 1 Habitat specialists -20 0.5 Wider countryside species -30 Regular migrants No. days advance advance No.days 0 -40 1976 1981 1986 1991 1996 2001 2006 2011 -50

Figure 4. The Composite Collated Index for habitat specialists -60 (n=28), wider countryside species (n=25) and regular migrants (n=3). Figure 5. The advance in flight periods in 2011 measured as the difference between the earliest date of mean abundance in With the inclusion of Swallowtail and Glanville 2011 and the average earliest date of mean abundance for the series (1976-2011). Negative values represent advances (red Fritillary (Appendix I) we are able to report on 23 points) whereas positive values show a delay in the flight period Biodiversity Action Plan# (BAP) priority species. Of (blue points). these, 13 species increased between 2010 and 2011 whilst 10 declined, with a higher proportion of As one might expect, the stage at which a butterfly increasing species representing a reversal of fortunes. overwinters affects its phenological response. Those Priority species have significantly declined since 1976, species that spend winter in the adult stage (n = 4) by almost 50%, so year on year increases in both 2010 showed the largest advances, being able to take and 2011 are welcome. As mentioned, a number of the advantage of any warm weather by emerging from spring and early summer species, such as Pearl- overwintering without any development required bordered Fritillary and Duke of Burgundy, did well but (Figure 6). The next greatest advances were shown by this was counterbalanced by those flying later in the those species that overwinter in the pupal stage (n = 10), year, such as Brown Hairstreak and White Admiral, with no difference between species overwintering in which were badly affected by the poor weather. larval (n = 30) or egg (n = 9) stages for which the smallest advances were shown. Although one might # The ‘UK Post-2010 Biodiversity Framework’ succeeded UK BAP in expect that warmer temperatures should advance the July 2012.

6 BUTTERFLY ABUNDANCE IN 2011

development of the larvae and allow them to feed earlier herbaceous forbs (n = 31) showing the greatest advances in the year, many of these species will have been in the and species feeding on woody plants and trees (n = 7) pupal stage when the weather became cooler. In intermediate between the two (Figure 7). Whilst the addition, it was a cold winter, which will have prevented majority of grass feeders are mid-late summer species overwintering larvae from feeding during the winter (the browns and the golden skippers) and therefore we months as they can do if it becomes mild enough. Cold might expect to see them showing the smallest winters are unlikely to have such pronounced effects on advances, there are some that appear earlier in the year pupal development in this way. such as Speckled Wood and Wall Brown and equally there are a number of species that fly later in the year 45 that feed on woody and herbaceous plants, including the 40 second generations of a number of species. 35 30 25 25 20 2011 20 15 15 10

5 2011 No. days earlier than average in earlierNo.days than average 10 0 Egg Adult 5 Overwintering stage No. days earlier than average in in earlier average than days No. Figure 6. Themean (+/- standard error) number of days earlier 0 species’ flight periods were in 2011 compared to the series Grass Herb Woody (1976-2011) average, grouped by the overwintering stage of Host plant type individual species. Figure 7. The mean (+/- standard error) number of days earlier There seemed to be no phenological differences species’ flight periods were in 2011 compared to the series (1976-2011) average, grouped by the type of larval host plant of between butterflies based on adult size, with smaller individual species. species showing similar advances to larger species. However, those species that feed on grasses (n = 15) showed the smallest advances with species feeding on

7 BUTTERFLY ABUNDANCE IN 2011

Table 2a. Summary of species abundance changes in the UK from 2010 to 2011 and long-term (over the entire time series; no. yrs max = 36) and short-term (last 10-years) changes. Significance of trends: * P <0.05 (significant), **P < 0.01 (highly significant), ***P < 0.001 (very highly significant). Red text has been used to highlight those species that had their worst year of the series in 2011, and blue text for those species that had their best year of the series in 2011.

No. sites No. years 2011 % change Start with with rank 2010-2011 Series 10-year SPECIES Year Index in 2011 Index in 2011 trend trend

Small Skipper 1976 517 36 34 -3 -70*** -66** 1977 286 35 33 10 -56 -92** 1992 12 20 17 84 -87*** -92*** Silver-spotted Skipper 1979 32 33 9 -13 >1,000*** -19 1976 576 36 16 -3 -14 3 1976 281 36 4 26 -31* 31 Grizzled Skipper 1976 232 36 4 96 -34 23 Swallowtail 1976 5 32 2 41 95* 18 Wood White 1979 52 33 18 -41 -83** -55 Clouded Yellow 1979 319 33 20 41 580 -97* Brimstone 1976 546 36 15 7 16 -5 Large White 1976 619 36 30 -19 -26 8 Small White 1976 613 36 21 -4 -17 -14 Green-veined White 1976 609 36 11 -5 -1 20 Orange-tip 1976 666 36 1 32 17 36 Green Hairstreak 1976 315 36 11 20 -34* -15 Brown Hairstreak 1983 50 29 26 -27 12 -50 Purple Hairstreak 1976 266 36 15 -7 -3 -15 White-letter Hairstreak 1976 124 36 31 -16 -82*** -22 Black Hairstreak 1995 10 16 7 -65 85 319 Small Copper 1976 547 36 17 -19 -19 30 Small Blue 1978 137 34 6 26 24 83 Silver-studded Blue 1979 55 33 11 4 17 -15 Brown Argus 1976 365 36 9 -31 26 44 Northern Brown Argus 1979 34 33 23 21 -58* -20 Common Blue 1976 578 36 21 -59 -1 -11 Chalkhill Blue 1976 153 36 11 -17 14 15 Adonis Blue 1979 81 33 14 -50 167* -1 Holly Blue 1976 563 36 16 -5 157 -28 Large Blue 1983 21 29 7 -21 >1,000*** -7 Duke of Burgundy 1979 93 32 24 65 -44* -51 White Admiral 1976 179 36 28 -51 -52** 21 Purple Emperor 1979 57 33 23 -50 48 -24 Red Admiral 1976 612 36 5 123 326*** -13 Painted Lady 1976 472 36 29 -16 341 -84 Small Tortoiseshell 1976 605 36 33 -22 -69** -75* Peacock 1976 657 36 33 -35 29 -17 Comma 1976 582 36 16 -22 296*** -6 Small Pearl-bordered Fritillary 1976 109 36 13 17 -56*** 40 Pearl-bordered Fritillary 1976 99 36 8 103 -72*** -11 High Brown Fritillary 1978 68 34 31 0 -50 -64* Dark Green Fritillary 1976 264 36 2 23 149** 88 Silver-washed Fritillary 1976 325 36 4 -31 116** 80 Marsh Fritillary 1981 87 31 18 -67 42 42 Glanville Fritillary 1992 11 20 2 129 -35 >1,000*** Heath Fritillary 1981 32 31 29 -5 -78*** -72** Speckled Wood 1976 586 36 4 12 145*** 12 Wall Brown 1976 289 36 35 -20 -83*** -62** Scotch Argus 1979 9 33 14 10 136* -44 Marbled White 1976 391 36 20 18 53 -16 Grayling 1976 134 36 28 -38 -59*** 43 Gatekeeper 1976 587 36 33 -13 -30 -46* Meadow Brown 1976 638 36 26 28 4 -30 Small Heath 1976 479 36 17 5 -55** 7 Large Heath 1990 11 22 1 12 362*** 130 Ringlet 1976 633 36 4 -13 334*** 38

8 BUTTERFLY ABUNDANCE IN 2011

Table 2b. Summary of species abundance changes for England, Scotland and Wales (where calculable) from 2010 to 2011 and long-term (over the entire time series; no. yrs max = 36 for England and Wales, 33 for Scotland) and short-term (last 10-years) changes. Significance of trends: P <0.05 (significant), **P < 0.01 (highly significant), ***P < 0.001 (very highly significant). Note: some country-level changes are based on relatively small sample sizes and thus should be interpreted with caution.

No. sites used % Change in Collated Index for trend 2010-2011 SERIES TREND 10-YEAR TREND SPECIES Eng Scot Wales Eng Scot Wales Eng Scot Wales Eng Scot Wales 502 - 14 0--20 -71*** - -27 -67** - -30 Essex Skipper 286 --10 ---56 ---92** -- Lulworth Skipper 12 --84 ---87*** ---92*** -- Silver-spotted Skipper 32 ---13 -->1,000*** ---19 -- Large Skipper 561 - 13 -4 - -9 -10 - -66*** 2--19 Dingy Skipper 276 -426 ---26 --33 -- Grizzled Skipper 231 --96 ---35* --23 -- Swallowtail 5--41 --95* --18 -- Wood White 50 ---26 ---82** ---53 -- Clouded Yellow 309 -531 --610 - -98 -97* - -100 Brimstone 542 --4--16 - 51 -6 -- Large White 578 15 15 -17 -54 -36 -25 114 -22 7 -16 22 Small White 579 13 13 -2 -80 -72 -13 6 -69*** -15 -49 -17 Green-veined White 571 16 15 0 -24 -43 -4 -4 102 17 11 261* Orange-tip 630 17 13 35 58 32 6 500*** 367** 27 410*** 94* Green Hairstreak 304 6-21 32 - -39 91** - 11 74 - Brown Hairstreak 49 ---27 --12 ---49 -- Purple Hairstreak 259 ---7 ---6 ---16 -- White-letter Hairstreak 122 ---14 ---82** ---29 -- Black Hairstreak 10 ---65 --85 --319 -- Small Copper 517 12 10 -24 35 -5 -12 -23 -41 30 267 40 Small Blue 137 --26 --25 --84 -- Silver-studded Blue 52 --3---23 ---28 -- Brown Argus 359 ---31 --30 --44 -- Northern Brown Argus 30 --20 ---71*** ---20 -100 - Common Blue 541 18 10 -60 15 -18 0 26 33 -11 -22 38 Chalkhill Blue 153 ---17 --14 --15 -- Adonis Blue 81 ---50 --167* ---1 -- Holly Blue 551 -7-7 - 24 168 - -13 -27 - 27 Large Blue 21 ---21 -->1,000*** ---7 -- Duke of Burgundy 93 --65 ---44* ---51 -- White Admiral 179 ---51 ---52** --21 -- Purple Emperor 57 ---50 --48 ---24 -- Red Admiral 568 22 14 131 62 -13 334*** >1,000* 214** -16 -20 10 Painted Lady 450 11 7 -14 -52 -62 360 -41 23 -84 -73 -87 Small Tortoiseshell 557 25 12 -24 -28 15 -70** -44 -29 -76* -17 -50 Peacock 611 22 16 -35 -24 -35 31 338** -25 -17 94 -22 Comma 563 6 10 -22 32 -47 299*** -2 61 -6 -2 154 Small Pearl-bordered Fritillary 90 13 6 29 -65 17 -33 -33 -29 40 -19 80* Pearl-bordered Fritillary 86 2 11 130 48 23 -51* 33 86 -21 33 9 High Brown Fritillary 59 -90---51 ---65* -- Dark Green Fritillary 231 20 11 20 7 32 355*** -36 -84*** 70 176*** 56 Silver-washed Fritillary 315 -6-29 --131*** --77 -- Marsh Fritillary 74 ---69 ---58 - -83** 40 -- Glanville Fritillary 6--128 ---33 -->1,000** -- Heath Fritillary 32 ---5 ---78*** ---72** -- Speckled Wood 559 7 10 12 15 -34 145*** 25 170*** 12 46 12 Wall Brown 274 - 11 -11 - -64* -85*** - -62** -63* - -52 Scotch Argus -5--11 --21 ---37 - Marbled White 389 --21 --51 ---17 -- Grayling 115 77-36 -47 0 -37* -64** -90*** 44 -38 184* Gatekeeper 568 - 13 -13 - -36 -35* - 100** -46* - -24 Meadow Brown 588 25 14 31 -34 24 4 19 44 -29 -50 -8 Small Heath 434 25 11 8 -33 -9 -60*** 160** 23 4 63 23 Large Heath -6---51 ------Ringlet 584 28 15 -13 -17 2 341*** 71 197*** 41 -10 63

9 UKBMS

Family overview in 2011, with all species showing annual declines and the grouped measure of abundance down by over a For each family of butterflies we provide brief third. However the long-term trend for this group is descriptions of trends from composite analyses. These classed as stable. It was a mixed year for migrant composite analyses exclude migrants and rare species species - Painted Lady declined and had a below with insufficient data. average year, whilst Red Admiral showed a large increase and produced its fifth best year on record. Skippers (Hesperiidae) Skippers had a good year, with a 23% increase over Fritillaries () 2010 in the combined index for this group. Four of the The fritillaries had a mixed year in 2011 with four seven species showed annual increases. However, in the species having a good year (particularly Pearl- last 10 years there have been significant declines in a bordered and Glanville Fritillaries), one species number of species and the short-term trend for this showing no annual change, and three species showing group is of a significant decline of almost 60%. Much of declines from 2010 levels. Over the long-term, this this recent decline is attributable to the declines group of butterflies has declined significantly by a third observed in the ‘golden’ skippers. since 1976, but, thanks to conservation management at a number of sites throughout the UK, it has stabilised over Swallowtails (Papilionidae) the last 10 years, even showing a small increase (18%). There is only one representative species, the Some species still remain rare and are of high Swallowtail, in this group found on monitored sites, for conservation concern. which details are provided in the species account. Most of the data is for the resident subspecies Papilio Browns (Satyridae) machaon britannicus, but there are occasional records This group of butterflies (10 species) consists of a of migrant individuals on monitored sites away from the number of our most abundant species which characterise resident East Anglian populations, presumed to be the mid-late summer transects. Populations of such species continental form (P.m.gorganus). have tended to remain relatively stable, with the exception of Small Heath, whilst there are contrasting Whites (Pieridae) fortunes for a number of other browns such as the Despite a superb year for Orange-tip, the whites as a Speckled Wood which has shown a significant increase, group had a below average year, with the combined and the Wall Brown which has significantly declined. index 8% lower than in 2010. Four species showed Overall the group had a very average year in 2011, annual declines, including the three commonest UK showing a small decline of 2% over 2010 with six species, Large, Small and Green-veined Whites. The species showing annual increases and four species long-term trend for this group is classed as stable. showing annual declines. The long-term and 10-year trends for the browns as a group are both classed as Blues, Coppers and Hairstreaks () stable, showing little or no overall change. Although the It was a mixed, but generally poor year for this group majority of UK butterflies had mean flight dates with abundance reduced by about a fifth from 2010. The advanced by a week or more in 2011, six of the nine combined long-term trend for this group is classed as browns assessed had mean dates within a week of the stable. Overall they declined by 21% in 2011 compared series average. to 2010. The decline was attributable to the blues which had a great year in 2010 and inevitably produced lower indices in 2011 given the poor late summer weather. The hairstreaks also fared rather poorly with the exception of Green Hairstreak, notably the only early flying member of this family.

Metalmarks (Riodinidae) The metalmarks are represented by just one species in the UK, the Duke of Burgundy. This is one of our rarer butterflies and has declined significantly since monitoring began in 1976. It recovered somewhat in 2011.

Vanessids, Emperors and Admirals (Nymphalidae) Bure Marshes – one of the top transect sites for the Swallowtail The five resident Vanessids had a particularly poor year with records going back to the beginning of monitoring in 1976. Photo by Alan Dawson

10 BUTTERFLY ABUNDANCE IN 2011

Species accounts In the following species accounts we present a summary (Carterocephalus palaemon) of how each species fared on UKBMS sites in 2011. For Chequered Skipper produced an annual index on just a species with insufficient data we briefly describe patterns single site in 2011, Glasdrum in Strathclyde. It has been on their main sites. The mean flight date is calculated as recorded at this site for nine years during which there the weighted mean date of counts as described in the has been a very small and non-significant decline in phenology article in the 2008 UKBMS annual report abundance and the population is classed as stable. Like (Botham et al. 2008). This is highly correlated to both other species flying early in the year, Chequered first appearance and the peak flight date. A Collated Skipper was out almost a week earlier than the average Index plot is included for each species. Horizontal across all years it has been recorded at Glasdrum, with a dashed lines show the average index value for the series. mean flight date of 26th May. Red lines show significant negative long-term trends, and blue lines show significant positive long-term trends (see Table 2a for trend details). Where neither of these lines are present the long-term trend is not statistically Small Skipper ( sylvestris) significant. The shaded area highlights the last ten years No. years with 36 2011 Rank: 34 of indices, with the trends presented in Table 2a. Country Collated Index: level statistics are presented for each species, where this Change in Collated Index -3 Long-term -71*** is calculable (Table 2b). 2010-11 (%): trend (%): Mean flight date 2011: 12-July Series mean 20-July flight date: denotes that the species is listed on the recent Butterfly Red List for Great Britain (Fox et al Collated Index plot: 2011) under one of the following categories: Critically Endangered, Endangered, Vulnerable or Near Threatened. G G G G G G G G G G G G G G denotes that the species was listed as a UK G G G G GGG G G G G G G G G BAP priority species between 1992 and 2012 G G G

(http://www.ukbap.org.uk) Collated Index G G G G 10 log 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 Year The Small Skipper remains at a low ebb with 2011 the third worst year on record. The Collated Index has been below average each year since 1997, whilst abundance has dropped by more than 70% since 1976. The largest annual index of 311 was recorded at Botley Wood in Hampshire. Almost 50% of the top ten transect counts came from Hampshire with Southwood Meadows topping the list on 2nd July with 94.

The mean flight date was the same as in 2010, being eight days earlier than the series average.

Chequered Skipper. Photo by Chris Barlow'

Skippers (Hesperiidae) 11 BUTTERFLY ABUNDANCE IN 2011

Essex Skipper (Thymelicus lineola) Lulworth Skipper (Thymelicus acteon)

No. years with 35 2011 Rank: 33 No. years with 20 2011 Rank: 17 Collated Index: Collated Index: Change in Collated Index 10 Long-term -56 Change in Collated Index 84 Long-term -87*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 14-July Series mean 24-July Mean flight date 2011: 18-July Series mean 28-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index G G G G G

10 G 10 G G G G log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

The Essex Skipper has been in progressive decline since The rarest of our golden skippers, the Lulworth Skipper the mid-2000s, with 2011 producing the second worst has declined significantly by a shocking 87% since the index of the series. There were few three-figure indices, start of monitoring. Having produced its lowest index the largest being 142 at Little Wittenham, Hill Farm in for four years in a row in 2010, it was good to see some Oxfordshire and 131 at Pilot Hill in Hampshire. recovery in 2011, although numbers were still well below average and this remains a species of Although very similar in appearance to the Small conservation concern. A repeat survey of sites is Skipper, the Essex Skipper overwinters as an egg rather currently being undertaken to investigate the scale of the than a larva, and perhaps this has something to do with decline and possible causes. why the two species had different fortunes in 2011? The highest site index (and the only one in three figures) of 266 was recorded at Durlston Country Park West in Dorset. The maximum count (again at Durlston) was 63 on 1st August. The hot spring weather had a great impact on this species with the average mean flight date 10 days earlier than the series average.

Essex Skipper. Photo by Guy Freeman

12 Skippers (Hesperiidae) BUTTERFLY ABUNDANCE IN 2011

Silver-spotted Skipper ( comma) Large Skipper ( sylvanus)

No. years with 33 2011 Rank: 9 No. years with 36 2011 Rank: 16 Collated Index: Collated Index: Change in Collated Index -13 Long-term >1000*** Change in Collated Index -3 Long-term -14 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 16-Aug Series mean 15-Aug Mean flight date 2011: 25-June Series mean 05-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index G G G G 10 10

G log G log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Although there was a modest drop in numbers, 2011 There was a small drop in Large Skipper abundance in was still well above average for Silver-spotted Skipper. 2011 and considerably fewer sites recorded three-figure This butterfly has been doing extremely well since the indices (33 compared to 44 in 2010). Whilst Pamber mid 1990s, with abundance over the series up by more Forest in Hampshire produced the highest of these than 1,000%. Four sites recorded three-figure indices, (482), it was at Middle Harling Heath in Norfolk that the the maximum being 303 at Malling Down in East maximum weekly count of 110 was recorded. The long- Sussex. This site also recorded the largest day count of term trend for the butterfly is classed as stable. 109 on 5th August. It was an early year, with the mean flight date advanced by 10 days from the series average.

Silver-spotted Skipper habitat at Malling Down, East Sussex. Photo by Ian Cunliffe

Skippers (Hesperiidae) 13 BUTTERFLY ABUNDANCE IN 2011

Dingy Skipper (Ennis tages) Grizzled Skipper ( malvae)

No. years with 36 2011 Rank: 4 No. years with 36 2011 Rank: 4 Collated Index: Collated Index: Change in Collated Index 26 Long-term -31* Change in Collated Index 96 Long-term -34 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 14-May Series mean 01-June Mean flight date 2011: 07-May Series mean 29-May flight date: flight date:

Collated Index plot: Collated Index plot:

G G G

G G G GG G G G G G G G G G G GG G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G GGG G G G G G G G G G G G G Collated Index Collated Index 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Dingy Skipper had its fourth best year on record with Grizzled Skipper had a fantastic year with abundance annual abundance up by a quarter. There was some almost double that of 2010. For the first time since 2002 evidence for range expansion with five long-running more than a single site produced a three-figure index transects recording the butterfly for the first time. Three- and there were 21 sites where abundance exceeded 50 figure indices were recorded at 11 sites with a maximum (Figure 8). Levin Down in West Sussex recorded the of 244 at Folkestone Escarpment in Kent. Most of the highest index (165) as well as the maximum weekly larger site indices were obtained from central and southern count of 40 on 20th April. Grizzled Skipper was England (Figure 8). The maximum day count was 81 at recorded extremely early on transects in 2011,with the Lullington Heath in East Sussex on 10th May. mean flight date over three weeks earlier than the long- term average. The first transect records on 6th April at This is now the second year running in which the Dingy Fontmell Down in Dorset and Magdalen Hill Down in Skipper has produced an index above the series average Hampshire were more than a week earlier than 2010. and the third year in a row in which it has shown an annual increase. However, the butterfly remains in long-term decline with abundance reduced by almost a third since 1976. The mean flight date was more than two weeks earlier than 2010 and the series average.

Sites producing indices > 50

!( Dingy Skipper only !( Grizzled Skipper only

(! Dingy and Grizzled Skippers

!(

!( !( !( !( !( (! !(!( !(( !( !( !( (!!(!( !( !( !( !(!( !(!(!(!( !( !( !( (! (!!((!!( (! !( !((! !(!(!( !((! !( !(!( !(!( !(

Dingy Skipper. Photo by Ben Woodward Figure 8. Sites producing an index of 50 or greater for Dingy and/or Grizzled Skippers in 2011.

14 Skippers (Hesperiidae) BUTTERFLY ABUNDANCE IN 2011

Swallowtail (Papilio machaon) Wood White (Leptidea sinapis)

No. years with 32 2011 Rank: 2 No. years with 33 2011 Rank: 18 Collated Index: Collated Index: Change in Collated Index 41 Long-term 95* Change in Collated Index -41 Long-term -83** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 15-June Series mean 18-June Mean flight date 2011: 01-June Series mean 18-June flight date: flight date:

Collated Index plot: Collated Index plot:

GG

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index

10 G 10 log log 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 3.0 4.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Indices for Swallowtail were generated from five Although down from the previous year, 2011 abundance Norfolk fens in 2011. Annual abundance was up by 40% was around the long-term average and well above levels and it was the second best year on record. Here we between 2006 and 2009. Given that the butterfly has present a long-term trend for the first time, which shows become extinct from so many monitored sites new a significant 95% increase on monitored sites since 1980. monitored sites are needed to improve coverage. It is pleasing to report that the butterfly was monitored at more sites than ever before.

The largest site index was 418 at Wigmore Rolls in the West Midlands. This site also recorded the maximum count with 83 on 24th May. Although there is no apparent short-term trend, this is still a species in trouble with a significant decline of more than 80% since 1979.

Our knowledge of the Wood White phenology has been updated thanks to collaboration with Stephen Jeffcoate who has studied the species in detail. At the beginning of monitoring Wood White generally produced just one brood on monitored sites, but over time it has produced a second brood on most sites.

Wood White voltinism seems highly variable, like a number of other species such as Dingy Skipper, and in warm years most sites produce a second brood, whilst in Swallowtail. Photo by Matthew Berry cooler years many do not. This variability is demonstrated by the mean flight date being more than The highest site index was 117 at Sutton Fen where the two weeks earlier than the long-term average. maximum day count of 26 was recorded on 1st June. A site index of 53 was the highest in over 15 years and the third highest since 1976.

Swallowtails (Papilionidae) - Whites (Pieridae) 15 BUTTERFLY ABUNDANCE IN 2011

Cryptic Wood White (Leptidea juvernica) Brimstone (Gonepteryx rhamni)

No. years with 36 2011 Rank: 15 The Cryptic Wood White has been regularly recorded at Collated Index: three UKBMS sites in recent years, but has been Change in Collated Index 7 Long-term 16 recorded on 10 different sites over the series. At the 2010-11 (%): trend (%): longest running of these sites, Murlough in County Mean flight date 2011: 18-May Series mean 09-June flight date: Down, abundance has significantly increased since 1981. Collated Index plot: Only Killykeeghan & Crossmurrin Nature Reserve in Fermanagh produced an index in 2011 although the butterfly was recorded on four sites including Murlough, and Craigavon Lakes and Oxford Island in G G G G G G G G GGG Armagh. The maximum day count was recorded at G G G G G G G G G G G G G G G G G G G G G G G G Craigavon Lakes with 68 on 13th of May. G Collated Index 10

Clouded Yellow (Colias croceus) log 1.0 1.5 2.0 2.5 3.0 No. years with 33 2011 Rank: 20 Collated Index: 1976 1981 1986 1991 1996 2001 2006 2011 Change in Collated Index 41 Long-term 580 Year 2010-11 (%): trend (%): Mean flight date 2011: 23-Aug Series mean 09-Aug flight date: 2011 was a slightly above average year, with a modest annual increase of 7%. However, three-figure indices Collated Index plot: were produced at more than 50 sites, 20 more than in 2010, the largest of which was 442 at Stockbridge Down in Hampshire. The same site recorded a maximum count G G G G of 72 on 3rd May. G G G G G G G G G

G G G G Brimstone shows a particularly stable trend over time G G G G G G G with small fluctuations annually. If one separates the G G G

Collated Index G G G counts into those for the spring period (post-

10 G G G overwintering adults from the previous year) and those log for the summer period (offspring of those adults that 0.0 1.0 2.0 3.0 4.0 overwintered from the previous year) these annual 1976 1981 1986 1991 1996 2001 2006 2011 fluctuations can be seen even more clearly (Figure 9). Year 2011 was dominated by spring period records with 83% of counts of 20 or more individuals before July. 2011 was a below average year for Clouded Yellow, but 90 .22 still an improvement over 2010, with an annual increase lsidua of more than 40%. Though numbers on individual sites 80 152.15 iduaindivr eta iduaindivr .12 were relatively low, it was recorded on 319 different 70 xd Inde xd 052.05 sites, the most since 2006, and more than 50 more than 60 aergr o02f os o02f aergr d Indeetllao CgLo 2 Indeetllao d in 2010. The main influx of this migrant butterfly was 50 95951. later than in 2010, and was generally quite late with the 40 .91 mean flight date two weeks later than the series average. 30 85851. stunocf o% stunocf 20 The largest site index was recorded at Longis on Spring .81 10 Summer Alderney with a meagre 17, most of which were Abundance 751.75 0 1.7 recorded on one visit on 14th June. On mainland UK,

Alton Water in Suffolk recorded the highest index of 1992 1993 1994 1995 1996 1996 1997 1998 1999 2000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 nine with a maximum count of eight on 2nd August. Figure 9. Percentage of counts that were of 20 or more individuals made on transects in the spring period (post- overwintering adults) and the summer period (offspring of previous year’s adults/pre-overwintering adults) over the last 20 years. The log Collated Index is also shown on the right- hand axis.

16 Whites (Pieridae) BUTTERFLY ABUNDANCE IN 2011

Annual abundance was down by about a fifth, with 2011 the seventh worst year in the 36-year series. Some of the largest annual declines occurred at sites with large populations in south-east and eastern England, with greater than 80% declines at Wood Lane Pirton in Hertfordshire, Hounslow Heath in Middlesex and Holkham in Norfolk.

The number of three-figure indices in 2011 was the third lowest in the last 10 years, almost half of that in 2010 and less than a quarter of that in 2009 (which was a record year). The largest site index was 363 at Windmill Hill, Chalton in Hampshire where a maximum count of 182 was recorded on 19th July. Populations on Brimstone. Photo by Chris Bradbury monitored sites fluctuate greatly from year to year with no apparent trend over the long-term. In 2010 the percentage of records was similar between the spring and summer periods, but in 2009 there was a Large White was another species whose flight period slightly greater percentage for the summer period and in was greatly affected by the incredible spring weather – 2008 the reverse of 2011 was true, with more than 70% the mean flight date was almost two weeks earlier than of counts of 20 or more individuals in the summer period. the series average.

Interestingly, the annual collated indices closely follow the spring period counts, such that when a greater Small White (Pieris rapae) percentage of all the high counts are made during the No. years with 36 2011 Rank: 21 spring period the annual index is high, whereas in years Collated Index: when a greater percentage of the high counts are made in Change in Collated Index -4 Long-term -17 2010-11 (%): trend (%): the summer period the index is low. With this in mind one Mean flight date 2011: 10-July Series mean 23-July might expect low numbers of high counts in the spring flight date: period for 2012 and a subsequently lower collated index? Collated Index plot: Brimstone was on the wing early in 2011with the mean flight date three weeks earlier than the average since 1976. G G G G G G G G G G G G G G G G G G G G G G G G G G G G G GG G Large White (Pieris brassicae) G G G G Collated Index

No. years with 36 2011 Rank: 30 10 Collated Index: log Change in Collated Index -19 Long-term -26 2010-11 (%): trend (%): 1.0 1.5 2.0 2.5 3.0 Mean flight date 2011: 09-July Series mean 21-July 1976 1981 1986 1991 1996 2001 2006 2011 flight date: Year

Collated Index plot: Annual abundance dropped by 4% with 2011 ranking as a below average year. Barking Riverside in Greater

G London, a site new to the scheme in 2011, recorded an G G G index of 2,051, with three-figure counts in five different G G G G G G G G G G G weeks. This is the third highest index on record. G G G G G G G G G G G G G G G G G G G However, the maximum count was recorded at G G

Collated Index Windmill Hill, Chalton in Hampshire, with an 10 impressive 315 on 4th July, almost double the maximum log count across the UK for 2010. In spite of an apparent 1.0 1.5 2.0 2.5 3.0 decline, the long-term trend is classed as stable. The 1976 1981 1986 1991 1996 2001 2006 2011 mean flight date was almost two weeks earlier than the Year long-term average.

Whites (Pieridae) 17 BUTTERFLY ABUNDANCE IN 2011

Green-veined White (Pieris napi) Orange-tip (Anthocharis cardamines)

No. years with 36 2010 Rank: 11 No. years with 36 2011 Rank: 1 Collated Index: Collated Index: Change in Collated Index -5 Long-term -1 Change in Collated Index 32 Long-term 17 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2010: 26-June Series mean 09-July Mean flight date 2011: 25-Apr Series mean 17-May flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

There was a slight drop in numbers but it was still an This univoltine spring species was one of the greatest above average year, ranking just outside the top 10. As benefactors of the superb spring weather in 2011, for the Small White, Barking Riverside took top spot for producing its best index of the series with an increase of Green-veined White with an index of 1,438 and a almost a third over 2010. This is on the back of a good maximum count of 361 on 17th August. In Wales, a year in 2010 and is the third year in succession that it third of sites recorded three-figure indices with 213 has shown an annual increase. No less than 23 different being the highest at Nine Wells in Pembrokeshire. The sites recorded three-figure indices in 2011, by far the butterfly has been doing well at a number of monitored most on record, with six in 1990 being the next highest. sites in Wales over the last decade. Numbers have The UK trend is classed as stable, though it has been increased by almost 20% at Whixall Fens and Mosses in spreading throughout Scotland. The combined site trend Clwyd, by more than 20% at Newport Wetlands in for Scotland shows a large increase over the series. Gwent and Whixall Moss in Clwyd and by almost 40% at Coed Maidie B Goddard in Ceredigion. Across the The highest site indices of 2011 were produced in UK the long-term trend is classed as stable. Scotland, both in East Lothian with 175 at Haddington Clerkington and 164 at Aberlady Bay. The maximum count was 67 on 28th April at Slievencloy in Antrim, but with a Scottish count close behind with 60 on the same day at Robroyston Parl Local Nature Reserve in Lanarkshire.

The Orange-tip is one of the species that has shifted its flight period the greatest as a result of recent climate warming. Its mean flight date was more than three weeks earlier than the series average in 2011 and it was first recorded on transects before the season began properly in late March.

Green-veined White. Photo by Tim Melling

18 Whites (Pieridae) BUTTERFLY ABUNDANCE IN 2011

Green Hairstreak (Callophrys rubi) Brown Hairstreak (Thecla betulae)

No. years with 36 2011 Rank: 11 No. years with 29 2011 Rank: 26 Collated Index: Collated Index: Change in Collated Index 20 Long-term -34* Change in Collated Index -27 Long-term 12 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 10-May Series mean 29-May Mean flight date 2011: 20-Aug Series mean 25-Aug flight date: flight date:

Collated Index plot: Collated Index plot:

G

G G G G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G GG GG G G G G G G G G G G Collated Index Collated Index

10 10 G log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Another of our spring species, the Green Hairstreak also Flying late in the season, it is probably little surprise that had a good year. This comes as particularly good news Brown Hairstreak had a poor year. Annual abundance after reaching a series low in 2009 and marks a third was reduced by more than a quarter, with 2011 being the successive year of increase and a return to above fourth worst year in the series. average numbers on monitored sites. This localised species is already extremely elusive and Long-term, the Green Hairstreak has declined thus numbers on transects are always quite low – few significantly, but over the last 10 years the population sites produce double figure indices and only in good has stabilised. As usual, the impressive numbers at years. One such site is Noar Hill in Hampshire which, Meathop Moss in Cumbria topped the leader board with with 13, recorded the highest index of 2011. Alners an impressive index of 1,532 and three weekly counts Gorse in Dorset, with an index of seven, recorded the above 300, with the maximum being 410 on 23rd April. maximum count of five on 31st July.

The mean flight date was close to the series average, reflecting the cooler temperatures typifying the late summer period.

Green Hairstreak. Photo by Matthew Berry

Blues, Coppers and Hairstreaks (Lycaenidae) 19 BUTTERFLY ABUNDANCE IN 2011

Purple Hairstreak (Favonius quercus) White-letter Hairstreak (Satyrium w-album)

No. years with 36 2011 Rank: 15 No. years with 36 10 Rank: 31 Collated Index: Collated Index: Change in Collated Index -7 Long-term -3 Change in Collated Index -16 Long-term -82*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 18-July Series mean 30-July Mean flight date 2011: 08-July Series mean 26-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G GGG G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G

Collated Index G Collated Index G 10 G 10 G log log 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 3.0 4.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

The Purple Hairstreak had a mediocre 2011, with a It was another disappointing year for the White-letter slight drop in annual abundance and a year rank of 15 Hairstreak, the sixth worst on record. Indices were low, out of 36. On standard transects, the largest index was except at Benfleet Down in Essex, where there was an 88 at Woodford Golf Course in Essex, whilst the increase from 50 in 2010 to 72 in 2011. This site also maximum weekly count was 30 at Minsmere in Suffolk recorded the maximum weekly count with 39 on the 1st on 19th July. July – this count being higher than the annual totals for all other sites. The largest annual change noted came from Bedelands Farm Nature Reserve in West Sussex, with 15 in 2010 Abundance across the UK has declined significantly and 38 in 2011, whilst it was a poor year at since monitoring began, though much of this decline Whippingham (fields) on the Isle of Wight with 82 in happened in the 1980s and 1990s. Since then the 2010 and 21 in 2011. Following a sharp decline in the population on monitored sites has stabilised but it is mid 1980s, Purple Hairstreak abundance has stabilised found in only small numbers on most sites. on monitored sites with seven of the last 10 years above the series average. The mean flight date was more than two weeks ahead of the series average. Although the mean flight date was almost two weeks earlier than the series average, Purple Hairstreak was first recorded as early as 3rd June on a transect and the first sighting as posted on the Butterfly Conservation website was even earlier – on 11th May.

20 Blues, Coppers and Hairstreaks (Lycaenidae) BUTTERFLY ABUNDANCE IN 2011

Black Hairstreak (Satyrium pruni) Small Copper (Lycaena phlaeas)

No. years with 16 2011 Rank: 7 No. years with 36 2011 Rank: 17 Collated Index: Collated Index: Change in Collated Index -65 Long-term 85 Change in Collated Index -19 Long-term -19 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 09-June Series mean 29-June Mean flight date 2011: 14-July Series mean 03-Aug flight date: flight date:

Collated Index plot: Collated Index plot:

G

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index 10 10

G log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Following a series peak in 2011, abundance dropped by Small Copper annual abundance was down by 19 % two-thirds. This is our rarest hairstreak, with only a with 2011 classed as an average year (ranked 17 of 36). very restricted range and thus there are only a few sites There were substantial annual decreases at a number of contributing data, 10 sites being the highest number in sites including from 284 to 76 at Sand Point in Avon, any one year. from 300 to 94 at Barbury Castle in Wiltshire and from 114 down to 22 at Westbury Beacon in Somerset. It also has a very narrow flight period and so can be highly susceptible to even short periods of bad weather. Cavenham Heath in Suffolk recorded the highest index However, the temperatures were still warm and there (521), as it has done for the previous two years, but the was plenty of sunshine in June 2011 when Black maximum count was 92 on 24th July at St. Abb’s Head Hairstreak was on the wing almost three weeks earlier in the Borders. Only one of the top ten counts was from than the series average, which suggests another factor the southern half of England, with sites in Scotland and such as parasitoids is more likely to have driven the northern England recording most of the highest counts. annual decline. This is a species which shows The Small Copper trend shows little or no overall considerable annual fluctuations and the apparent long- change over the series. term increase is not significant. Small Copper is continuously brooded on many sites In the previous two years the M40 Compensation Area with the first brood out in spring. It was first recorded on in Buckinghamshire recorded the highest indices, with a a transect in the third week of March at Walton Nature maximum of 45 in 2010. However, this population was Park in West Yorkshire and the mean flight date was reduced by almost 60% in 2011. A timed count set up in almost three weeks earlier than the series average. 2011 at Brampton Wood in Cambridgeshire took top spot for 2011, and for the series, with an index of 54. Although it is difficult to tease out third and fourth generations from the second, as they tend to overlap greatly, it is likely that there were multiple broods at a lot of sites due to the warm start to the year. However, numbers are often greater in the later broods with August or September registering the greatest numbers in all but one year since 1976. And, with the weather so poor in August 2011, numbers were less than 50% of those for the same month in 2010.

Blues, Coppers and Hairstreaks (Lycaenidae) 21 BUTTERFLY ABUNDANCE IN 2011

Small Blue (Cupido minimus) Silver-studded Blue (Plebejus argus)

No. years with 34 2011 Rank: 6 No. years with 33 2011 Rank: 11 Collated Index: Collated Index: Change in Collated Index 26 Long-term 24 Change in Collated Index 4 Long-term 17 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 07-June Series mean 30-June Mean flight date 2011: 25-June Series mean 17-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G G G Collated Index G Collated Index GG G 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

There was a modest increase in Small Blue abundance, For the third year in succession, there was little change with 2011 classed as the sixth best in the series. There in Silver-studded Blue abundance, with 2011 ranked were a number of notable increases on sites with smaller 11th in the 33-year series. The largest site index was colonies such as Banstead Downs in Surrey with an 2,504 at Upton Towans in Cornwall, with a peak count increase from 2 to 14, and Magdalen Hill Down North of 687 on 6th June. in Hampshire with an increase from 18 to 51 (nearby Magdalen Hill Down extension also recorded an It was an early year for the butterfly, with the mean increase from 2 to 15). flight date more than a week earlier than the series average. In spite of an apparent increase, the long-term By far the largest index of 2011 was recorded at trend is classed as showing little or no overall change. Durlston Meadows in Dorset, with an impressive 608, The mean flight date was more than three weeks earlier the sixth highest on record, and more than double that than the series average. for any other site. A peak count of 177 was made on 19th May at the same site. In spite of a modest increase across the UK in 2011, the long-term trend since 1978 shows little or no overall change. It was an early year with the mean flight date more than three weeks ahead of the series average.

Small Blue. Photo by Tony Morris

22 Blues, Coppers and Hairstreaks (Lycaenidae) BUTTERFLY ABUNDANCE IN 2011

Brown Argus (Aricia agestis) Northern Brown Argus (Aricia artaxerxes)

No. years with 36 2011 Rank: 9 No. years with 33 2011 Rank: 23 Collated Index: Collated Index: Change in Collated Index -31 Long-term 26 Change in Collated Index 21 Long-term -58* 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 09-July Series mean 01-Aug Mean flight date 2011: 26-June Series mean 12-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G

Collated Index G Collated Index G 10 10

log log G 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Following a good year, it was not surprising that there For the fourth year in a row Northern Brown Argus were fewer Brown Argus butterflies seen in 2011, with increased in abundance, though 2011 was still classed as abundance reduced by almost a third. There were 20 a below average year. sites where annual abundance decreased by 75% or more, including Pewsey Down in Wiltshire where the There were some positive counts in north-west England, index went from 325 to 37. with abundance more than doubling at Witherslack Hall Woods and Lancelot Clark Storth. The largest site A number of sites bucked the trend, including indices were also recorded in this region, with the Bonchurch Down on the Isle of Wight where the index maximum being 267 at Warton Crags RSPB Reserve. increased from 64 to 193. The three largest indices all came from Somerset, with the maximum being 395 at The largest weekly count was also recorded here, with Shute Shelve Hill. This site also recorded the highest 103 on 20th June. The last above average year for this weekly count with 110 on 3rd May. butterfly was as far back as the late 1990s and there has been a significant decline of 58% since the start of the Though the apparent increase in Brown Argus series in 1979. abundance since 1976 is not significant, there has been a range expansion in recent decades. A recent study led by The mean flight date was more than two weeks earlier Rachel Pateman and published in Science shows that than the long-term average. this spread is attributable to a change in host plant use driven by climate change (Pateman et al. 2012).

In common with many other species, it was an early year, with the mean flight date more than three weeks ahead of the series average.

Blues, Coppers and Hairstreaks (Lycaenidae) 23 BUTTERFLY ABUNDANCE IN 2011

Common Blue (Polyommatus icarus) Chalkhill Blue (Polyommatus coridon)

No. years with 36 2011 Rank: 21 No. years with 36 2011 Rank: 11 Collated Index: Collated Index: Change in Collated Index -59 Long-term -1 Change in Collated Index -17 Long-term 14 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 01-July Series mean 26-July Mean flight date 2010: 05-Aug Series mean 09-Aug flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G GG G G G G G G G G G G G G G G G G G G G G GGG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index G Collated Index 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Common Blue annual abundance dropped sharply in There was a modest decline in Chalkhill Blue 2011, with the butterfly going from having its second abundance in 2011, though it was still classed as an best year on record to having a below average year. above average year, ranked 11 out of 33. The largest There were 26 sites where abundance dropped by 90% annual index of 4,404 was logged at Devil’s Dyke, near or more, with the most spectacular being at Blunts Wood Newmarket in Cambridgeshire, whilst the largest single & Paiges Meadows in Sussex where an index of 2,669 count was 2,306 on 30th July at Friston Hill in Sussex. in 2010 was followed by an index of 112 in 2011. The long-term trend across UK sites is classed as A small number of sites did manage to produce showing little or no overall change. substantial increases though, with perhaps the most impressive at Cubert in Cornwall, where the index more Flying later in the year than the first broods of other than doubled from 123 to 304. The maximum day count grassland blues, Chalkhill Blue did not show the impact of the year was 242 at Buckland Wood in Somerset on of spring temperatures on its flight period that other 19th May. It was an advanced season for the Common species did and the mean flight date was similar to the Blue, with the mean flight date being more than three series average, earlier by just four days. weeks earlier than the series average.

Bindon Hill, Dorset - grassland Lycaenids such as Chalkhill Blues are abundant on this chalk grassland transect. Photo by Tom Brereton

24 Blues, Coppers and Hairstreaks (Lycaenidae) BUTTERFLY ABUNDANCE IN 2011

The first record on a transect, and potentially the earliest Adonis Blue (Polyommatus bellargus) sighting of Adonis Blue for the year, was on 23rd April

No. years with 33 2011 Rank: 14 at White Sheet Hill Quarry, a National Trust site in Collated Index: Wiltshire. The superb spring weather clearly favoured Change in Collated Index -50 Long-term 167* this highly thermophilic butterfly which utilises habitats 2010-11 (%): trend (%): where ground temperatures are greatest. Mean flight date 2011: 29-June Series mean 25-July flight date: The mean flight date was almost a month earlier than Collated Index plot: the series average.

G Holly Blue (Celastrina argiolus) G G G G G G G No. years with 36 2011 Rank: 16 G G G G G G G G Collated Index: G G G G G G G G G G Change in Collated Index -5 Long-term 157 G G G G G 2010-11 (%): trend (%): Collated Index G 10 Mean flight date 2011: 11-June Series mean 29-June G flight date: log 1.0 1.5 2.0 2.5 3.0 Collated Index plot: 1976 1981 1986 1991 1996 2001 2006 2011

G Year G

G G G Although Adonis Blue abundance was half that in 2010, G G G G G G G G G G G G it was still an above average year, ranked 14 in the G G G G G G G 33-year series. Unsurprisingly, there were far fewer G G G G G

large counts than in 2010 (second best year on record), Collated Index G G with the maximum index being 1,970 at Anchor Bottom 10 G G G in Sussex. The largest weekly count was made at log G G

Swanage in Dorset, with 446 on 6th May – a very early 1.0 1.5 2.0 2.5 3.0 date for such a count when compared to other years. 1976 1981 1986 1991 1996 2001 2006 2011 Year Unusually, all of the highest counts were associated with the first brood and many were very early. In fact, first There was little change in Holly Blue abundance in brood counts were much higher than on average across 2011. It was an average year, though the butterfly was the series, whilst second brood counts were recorded more widely than ever before (over 100 more considerably lower (Figure 10). sites than in any other year). However there was only one three-figure index (compared to three in 2010), this 90 Average 1979-2010 105 at Tower Hamlets Cemetery in Inner London. 80 2011 70 The Holly Blue has fluctuated markedly in abundance 60 since 1976, with the long-term trend classed as showing

50 little or no overall change.

40 The good weather at the start of the year brought the 30 first generation out early, and the mean flight date for 20 the whole year was more than two weeks earlier than the 10 error standard +/ - count Average series average. Very few sites recorded double figures 0 day counts. Apr May June July Aug Sep

Figure 10. Average monthly counts of Adonis Blue in 2011 against the average across all previous years (1979-2010) with standard error as error bars

Since 1979, this butterfly has increased significantly in abundance by around 170%.

Blues, Coppers and Hairstreaks (Lycaenidae) 25 BUTTERFLY ABUNDANCE IN 2011

Large Blue (Phengaris arion) Duke of Burgundy (Hamearis lucina)

No. years with 29 2011 Rank: 7 No. years with 32 2011 Rank: 24 Collated Index: Collated Index: Change in Collated Index -21 Long-term >1000*** Change in Collated Index 65 Long-term -44* 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 28-June Series mean 25-June Mean flight date 2011: 04-May Series mean 31-May flight date: flight date:

Collated Index plot: Collated Index plot:

G GG G GG G G G G G G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index G 10 10 G log log G 0.0 1.0 2.0 3.0 4.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Large Blue abundance was reduced by 20% in 2011, The Duke of Burgundy increased in abundance by though it was an above average year ranked seventh in almost two-thirds between 2010 and 2011. An increase the 29-year series. Of the public sites contributing of this rare and threatened species was extremely indices, Green Down in Somerset produced the largest welcome news, though in context, it was still a below index of 28. The mean flight date for Large Blue was average year ranked 24 in the 32-year series and the later in 2011 than the series average. butterfly remains in long-term decline.

Another positive from the season was that there were new records (counts of ones and twos) at four regularly monitored sites, bringing hope that new colonies will be established at these sites.

There were substantial annual increases at a number of sites including from 3 to 30 at Cerne Abbas Giant in Dorset, 8 to 25 at Thurlbear Quarrylands in Somerset and 25 to 75 at Whipsnade Downs in Bedfordshire. The largest site index was 201 at Noar Hill in Hampshire, where counts in excess of 50 were made on three days over the season. An index of 113 at The Mountain (Meon Valley) in Hampshire was also noteworthy.

It was an early year, with the mean flight date almost Large Blue habitat at Collard Down, Somerset. Photo by four weeks ahead of the long-term average. Morag McCracken

26 Blues, Coppers and Hairstreaks (Lycaenidae) - Metalmarks (Riodinidae) BUTTERFLY ABUNDANCE IN 2011

White Admiral (Limenitis camilla) Purple Emperor (Apatura iris)

No. years with 36 2011 Rank: 28 No. years with 33 2011 Rank: 23 Collated Index: Collated Index: Change in Collated Index -51 Long-term -52** Change in Collated Index -50 Long-term 48 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 02-July Series mean 18-July Mean flight date 2011: 07-July Series mean 22-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G GG G G G G G G G G G G Collated Index Collated Index G 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Following on from a good year in 2010, White Admiral Following three good years, Purple Emperor abundance abundance dropped substantially in 2011 by more than halved in 2011, with the year ranking 23 in the 33-year 50%. The combination of drought in the spring (to series. which the larval hostplant Honeysuckle is susceptible) and unsettled weather over the adult flight season are Of these, there were none where abundance was up on likely to have been contributory factors to the butterfly 2010 levels, and very few were seen, with the maximum having a poor year – the ninth worst in the series. day count being just three at Oakley Woods in Buckinghamshire on 1st July. Substantial declines included from 139 in 2010 to 39 in 2011 at Burnt Oak Wood in Kent and from 181 to 87 at The apparent increase in abundance since 1979 is not Pamber Forest in Hampshire. There were no major significant and the long-term trend is classed as showing increases noted. The butterfly has declined significantly little or no overall change. In common with the White in abundance since 1976 by more than 50%. Admiral, the mean flight date was advanced by more than two weeks. In spite of poor summer weather, the mean flight date was advanced by more than two weeks.

Purple Emperor and White Admiral are recorded together on transects in deciduous woodland with open rides in southern England such as Bernwood Forest, Buckinghamshire (pictured). Photo by Jackie Harman

Vanessids, Emperors and Admirals (Nymphalidae) 27 BUTTERFLY ABUNDANCE IN 2011

As might be expected, the majority of large indices were Red Admiral (Vanessa atalanta) recorded at sites on or near the coast (Figure 11),

No. years with 36 2011 Rank: 5 especially in southern England. Somerset was the Collated Index: standout county, logging the three highest indices. Change in Collated Index 123 Long-term 326*** 2010-11 (%): trend (%): These were: 370 at Ham Wall, 360 at Shapwick Heath, Mean flight date 2011: 28-July Series mean 07-Aug and 274 at Long Wood. It was a very good year in flight date: Suffolk as well, with three-figure indices at four sites, Collated Index plot: and the UK’s highest day count of 89 at Upper Abbey Farm on 13th September.

G G The Red Admiral has increased significantly in recent G G G G G decades, by more than 300%. G G G G G G G G G G G G G G G G G G G G G G G G Red Admiral G G Collated Index Indices 2011 10 G G !(!( G (! <= 10 log (! 11 - 20 !( 1.0 1.5 2.0 2.5 3.0 (! 21 - 50 (! 1976 1981 1986 1991 1996 2001 2006 2011 (! 50 - 100 !( !( !( (! > 100 Year !( !(

(! !(!( It proved to be a very good year for Red Admiral with an !( !( (!(! impressive 123% increase over 2010 levels, making it !( !( !( !( the fifth best year on record. Transect numbers peaked !( !(

in July with a total of 5,934 counted across 724 sites. !( (! !( (!! (!( !( Numbers dropped slightly but remained high throughout !( !(!( !( (! !( !( !(!( August and then rose again in September, when the !(!( !( !( (! !((!!( !( !(!( average number per transect was equal to that in July, (! !( !( though the butterfly was recorded from approximately !( !( (! !( (! !( !( !( !( !( one hundred fewer sites. !(!( !( !( !( (! !(!( (!(!!((! !( !( !( (!!( !( (! !( !(!( (!(!(! !( !(!(!(!( !( !( !( !(!( !!( (!!( ( !( !( ( (!(! (! (! !( ! (! !(!( (!!( (! (!(!(! (! !((!!(!(!((! !((!!((!!( !(!( ! (! ! !( !( !( (!!( !( !( (! !( ( ( !( (! !(!( ( !( !(!( (! !( !( (! !((! (!!( (! (! !( !( !((!(! !(!!(!(!((!(!!( (! !( !( !((!!(!(!( !(!(!((!(!(!(!(!( (! !( !( !( !( !(!(!(!( !(!(!( !( !( !( !((!!( !(!(!( !(!(!(!( (!(! (!(!!(!( (!!( !( !( !(!( !(!( !(!(!((!(! (! (! !(!(! !(!((!(!(!(!( !( (! (!!( (! !(! !( !((!!((! !((!!(( !(!(!(!(!(!( !(!( (! (!(!!((!(!!( (!( !( !( !(!(!(!((! ! !(!(!( !( !((!(! !(!( ((!!!((!( (! !( !( !((! !(!((!(!!(!((!(! (!!((!!(!( !(!(!(!(!( !( !( !!(!((! (!(!(!(!(!( !(!(!(!((!(! (!(! (! !( ( (! (!(!(!(!(! (!!(!(!((!!(!((! (!!(!((!(! (! !( (!!((! !(!(!((! !((!!(( !(!((!!((!!( (! (!(!(!!(((! !((!!(!( !( !( !(!(!(!((!(! !((! !( (!(! (! ( !((! !( (!(! (! (!

Figure 11. Site indices for Red Admiral in 2011.

Red Admiral. Photo by Matthew Berry

28 Vanessids, Emperors and Admirals (Nymphalidae) BUTTERFLY ABUNDANCE IN 2011

Painted Lady (Vanessa cardui) Small Tortoiseshell (Aglais urticae)

No. years with 36 2011 Rank: 29 No. years with 36 2011 Rank: 33 Collated Index: Collated Index: Change in Collated Index -16 Long-term 341 Change in Collated Index -22 Long-term -69** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 21-July Series mean 31-July Mean flight date 2011: 20-June Series mean 11-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G

Collated Index Collated Index GG G G 10 10 G G log log 0.0 1.0 2.0 3.0 4.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

It was a below average year for the Painted Lady with a Following two years of an improvement in fortunes, modest decline following 2010’s crash in numbers after Small Tortoiseshell declined in abundance once again in the huge 2009 influx. Only 10 sites produced double 2011, with abundance down by more than a fifth. figure indices, the maximum being 85 at Wootton Coppice in Hampshire. Abundance has been below average for 12 out of the last 14 years. Just seven sites produced a three-figure index, The maximum day count of 22 was recorded with the transect at Harper Adams in Shropshire considerably further north at the Caerlaverock Wildlife recording the maximum of 326. This site also recorded & Wetlands Trust Reserve in Dumfries and Galloway on the highest and only three-figure day count with 103 on 21st July. the 24th June.

In spite of an apparent increase, the long-term trend is There seemed to be a western bias with all of the top 20 classed as showing little or no overall change due to indices being in western England, Wales, or Scotland large annual fluctuations. with the exception of one site, Sutton Fen in Norfolk, in eastern England.

On the positive side, the butterfly remains widespread, being recorded on almost two-thirds of transects in 2011. The Small Tortoiseshell is now one of our most rapidly declining butterflies with abundance significantly reduced by nearly 70% since 1976.

The mean flight date was extremely early, being more than three weeks ahead of the series average.

Vanessids, Emperors and Admirals (Nymphalidae) 29 BUTTERFLY ABUNDANCE IN 2011

Large Tortoiseshell (Nympalis polychloros) Comma (Polygonia c-album)

No. years with 36 2011 Rank: 16 Encouragingly, there has been an increasing number of Collated Index: Large Tortoiseshell records on UKBMS sites in recent Change in Collated Index -22 Long-term 296*** years. In 2011 there were six records including a 2010-11 (%): trend (%): presumed migrant at Holkham in Norfolk on 11th July, Mean flight date 2011: 08-July Series mean 21-July flight date: and four sightings from the Isle of Wight in the early spring. The latter records from the Isle of Wight give Collated Index plot: hope that this butterfly may once again re-establish as a regular breeding species in the UK.

G G G G G G G G G G G G G G G G G G G G G G G G G G Peacock (Aglais io) G G GG G G G G No. years with 36 2011 Rank: 33 Collated Index G Collated Index: 10

Change in Collated Index -35 Long-term 29 log G

2010-11 (%): trend (%): 1.0 1.5 2.0 2.5 3.0 Mean flight date 2011: 07-June Series mean 03-July 1976 1981 1986 1991 1996 2001 2006 2011 flight date: Year Collated Index plot: The Comma declined in annual abundance by 22% in 2011, though it was still an above average year. Three- figure indices were produced at only two sites (the joint G G G G lowest number since 1990), compared to six sites in G G G G G G G G G GG G 2010 and 18 in 2009. The highest site index was at G G G G G G G G G G G G G G G G G G G Wyre Forest West in Hereford and Worcester, where G Collated Index abundance rose from 50 in 2010 to 335 in 2011. This 10 site also recorded the highest day count with 93 on 13th log May. 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 The Comma has been expanding in range rapidly and Year abundance has increased significantly by almost 300% since 1976. The increase in abundance has stabilised For the second year in a row Peacock abundance over the last decade, but the range expansion continues declined with an annual decrease of 35%, following on with at least two UKBMS transects recording the from the previous year’s drop of 30%, making 2011 the butterfly for the first time in 2011, including Sanford fourth worst year on record. Moor in Lanarkshire, Scotland.

A number of substantial annual declines were noted including from 105 to 18 at Whipsnade Downs in Bedfordshire and 115 to 19 at West Hallam Ash Tip in Derbyshire. However, a few sites performed well, with substantial annual increases noted at Ham Wall in Somerset (from 93 to 249) and at Cocklawburn in Northumberland (from 21 to 107).

During the 1990s the UK trend was classed as increasing, much of which was attributable to an expansion in range in Scotland.

The mean flight date was almost a month ahead of the long-term average. Through a run of poor years in the 2000s, the long-term trend is now classed as showing little or no overall change. Peacock. Photo by Tim Melling

30 Vanessids, Emperors and Admirals (Nymphalidae) BUTTERFLY ABUNDANCE IN 2011

Small Pearl-bordered Fritillary Pearl-bordered Fritillary (Boloria selene) (Boloria euphrosyne) No. years with 36 2011 Rank: 13 No. years with 36 2011 Rank: 8 Collated Index: Collated Index: Change in Collated Index 17 Long-term -56*** Change in Collated Index 103 Long-term -72*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 16-June Series mean 25-June Mean flight date 2010: 08-May Series mean 03-June flight date: flight date:

Collated Index plot: Collated Index plot:

G G

G G G G G G G G GG G G G G G G G G G GG G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index G 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

For the third year in a row the Small Pearl-bordered Pearl-bordered Fritillary annual abundance more than Fritillary increased, with abundance up by nearly a fifth doubled in 2011, with this being the best year for the over the 2010 level. For the first time since 1997, the butterfly since 1997 and the eighth best in the 36-year index was above the series average, with 2011 being the series. thirteenth best year in the series.

There were some impressive annual increases including from 23 in 2010 to 140 in 2011 at Wyre Forest in Pearl-bordered Fritillary Hereford and Worcester and from 21 to 96 at Bentley 2010-2011 No. butterflies % Change Wood (North) in Wiltshire. The highest index of 436 (! < = 10 (! < = 25 was logged at West Down in Devon, where annual !( 11 - 50 (! 26 - 50 (! 51 - 100 (! 51 - 100 abundance was up bymore more than 75%. This site (! > 100 (! > 100 recorded the only three-figure day count with 106 on the (! 29th April, with this being remarkably high for so early in the season.

In spite of an apparent increase over the last decade, the butterfly remains in significant long-term decline with abundance reduced by more than 50% since 1976. (!

Small Pearl-bordered Fritillary phenology is highly variable across the UK, though overall the 2011 season was a week earlier than the series average. !( !((!!( (!(! !( (!(! (!

(!(! (! (! (!(! !((!(!(!

Figure 12. Sites showing annual increases in Pearl-bordered Fritillary between 2010 and 2011. The size of the point refers to the absolute difference in the indices from 2010-2011 whilst the colour of the point refers to the percentage change in the indices.

Fritillaries (Nymphalidae) 31 BUTTERFLY ABUNDANCE IN 2011

Increases were widespread (Figure 12), and were most substantial in south-west England. Noteworthy Dark Green Fritillary (Argynnis adippe)

increases included from 17 in 2010 to 100 in 2011 at No. years with 36 2011 Rank: 2 Bentley Wood - Barnridge, from 23 to 99 at Bentley Collated Index: Wood – South, both in Wiltshire, from 96 to 274 at Change in Collated Index 23 Long-term 149** Pignal Inclosure in Hampshire, from 129 to 298 at Aish 2010-11 (%): trend (%): Tor in Devon, from 31 to 160 at Haugh Wood South in Mean flight date 2011: 14-July Series mean 22-July flight date: Hereford and Worcester and from 43 to 169 at Wyre Forest in Hereford and Worcester. Collated Index plot:

The largest site index was 356 at Hawksgrove in Bentley Wood, whilst the maximum weekly count was G

G G 148 on 24th April at Aish Tor. Annual declines were G G G G G G G G detected at only 5% of sites, but included a worrying G G G G G G G G G G G G G G drop from 150 in 2010 to 67 in 2011 at Eyarth Rocks G G G G G G G G G G Reserve in Clwyd. In spite of an increase in each of the Collated Index G last three years, the butterfly remains in significant long- 10 term decline with abundance reduced by almost three- log quarters since 1976. The butterfly was out almost a 1.0 1.5 2.0 2.5 3.0 month earlier than the series average on monitored sites. 1976 1981 1986 1991 1996 2001 2006 2011 Year

High Brown Fritillary (Argynnis adippe) Dark Green Fritillary abundance was above average for No. years with 34 2011 Rank: 31 the ninth consecutive year, with the annual rise of 23% Collated Index: qualifying 2011 as the second best year on record. Change in Collated Index 0 Long-term -50 Substantial increases included: from 13 in 2010 to 105 2010-11 (%): trend (%): in 2011 at Holkham in Norfolk, from 36 to 177 at Mean flight date 2011: 10-July Series mean 16-July Mottistone Down on the Isle of Wight and from 50 to flight date: 224 at Castle Hill in East Sussex. Collated Index plot: The butterfly fared less well in north-west England with only 4 of 17 sites showing an increase, all of which were G G relatively small. In the region, substantial declines were G G GG G noted at Gait Barrows where the index dropped from G G G G G G G 143 in 2010 to 22 in 2011 and at the National Trust G G G G G G G G G G G transect at Eaves Wood where numbers were down from G G G G G

Collated Index G GG 62 in 2010 to 9 in 2011. G 10

log The maximum day count was recorded on the Tower

1.0 1.5 2.0 2.5 3.0 Hill Wood transect at Porton Down in Wiltshire with an 1976 1981 1986 1991 1996 2001 2006 2011 impressive 391 on 4th July. On the same day Lullington Year Heath in East Sussex also recorded its highest day count of 218. High Brown Fritillary abundance showed no change in 2011, making it seven poor years in succession and one The Dark Green Fritillary has increased significantly on of the worst on record. Just 10 sites recorded three- monitored sites by almost 150% since 1976. In 2011, the figure indices (a third of the number recorded in mean flight date was advanced by just over a week previous good years), with the maximum being 670 at compared to the long-term average. Trentishore Combe in Devon (a timed count site). The maximum weekly transect count was 52 on 27th June at Warton Crag RPB Reserve in Lancashire. Due to large annual fluctuations in earlier years, the apparent long- term decline is not significant and the long-term trend is classed as showing little or no overall change. However, there has been a significant decline over the last decade with abundance reduced by more than two-thirds.

32 Fritillaries (Nymphalidae) BUTTERFLY ABUNDANCE IN 2011

Silver-washed Fritillary (Argynnis paphia) Marsh Fritillary (Euphydryas aurinia)

No. years with 36 2011 Rank: 4 No. years with 29 2011 Rank: 18 Collated Index: Collated Index: Change in Collated Index -31 Long-term 116** Change in Collated Index -67 Long-term 42 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 17-July Series mean 26-July Mean flight date 2011: 20-May Series mean 06-June flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index Collated Index G G G 10 10 log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Silver-washed Fritillary abundance dropped by almost a There was a substantial drop in Marsh Fritillary third in 2011, though numbers were still well above abundance in 2011 of more than two-thirds, with the average with the year classed as the fourth best in the year ranked below average. The largest site index was series. 316 at Cerne Abbas Giant in Dorset.

The largest site indices were 569 at Pamber Forest in Interestingly, whilst the adult count at this site was up by Hampshire and 723 at Bentley Wood (Hawksgrove) in more than double over 2010, the larval web count later Wiltshire, the latter site recording the day maxima of in the year was down by 90% and by more than a factor 141 on 11th July. of 10 compared to 2010.

There were first records from 13 regularly monitored The Marsh Fritillary can fluctuate considerably in sites (walked for at least the last five years), suggesting abundance from year to year due to parasitism, weather that the species is continuing to expand in range. and management effects (e.g. burning) and the apparent long-term increase is not significant. For the last nine years the index has been above the series average and there has been a significant increase The earliest record on monitored sites in 2011 was the in abundance since 1976 of more than 100%. The mean 6th May at Clubmens Down in Dorset and the mean flight date was over a week earlier than the series flight date was almost three weeks earlier than the series average. average.

Fritillaries (Nymphalidae) 33 BUTTERFLY ABUNDANCE IN 2011

Glanville Fritillary (Melitaea cinxia) Heath Fritillary (Melitaea athalia)

No. years with 20 2011 Rank: 2 No. years with 31 2011 Rank: 29 Collated Index: Collated Index: Change in Collated Index 129 Long-term -35 Change in Collated Index -5 Long-term -78*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 31-May Series mean 08-June Mean flight date 2011: 07-June Series mean 05-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G Collated Index G Collated Index G G G G G 10 10 log log 0.0 1.0 2.0 3.0 4.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Glanville Fritillary abundance more than doubled in There was no overall improvement in the fortunes of the 2011, with the year being the second best in the series. Heath Fritillary, with abundance reduced by 5% from 2010 levels, and 2011 classed as the third worst year in The trend for the Glanville Fritillary has been compiled the series. However, there have been positive signs in from six English (including two introduction sites) and recent years that this rare and threatened species is five Alderney, Channel Isles sites. On mainland UK, responding to targeted conservation management in abundance increased at Sand Point in Avon (an some areas. introduction site) from 15 in 2010 to 36 in 2011. The highest UK index of 122 came from Mottistone Down In 2011, positive annual changes on Exmoor sites on the Isle of Wight, whilst the maximum on Alderney monitored by timed counts included from 9 in 2010 to was 154 at Trois Vaux. 259 in 2011 at Hollow Combe, from 90 to 887 at Spangate, from 457 to 1,364 at Hanny Combe and from The apparent decline across all sites since 1992 is not 503 to 1,214 at Aller Combe. The butterfly had mixed significant and the long-term trend is therefore classed fortunes in Blean Woods in Kent. as showing little or no overall change. The mean flight date was nine days earlier than the series average. The largest index on a standard transect was 263 at Blean Woods RSPB Reserve and numbers were down at the Devon re-introduced site. The long-term trend remains a cause of conservation concern, with abundance reduced significantly by almost four-fifths since the early 1980s.

The Heath Fritillary was one of the species which showed the greatest advance in flight period in 2011, with the mean flight date almost a month earlier than the series average. The first record on a transect was on 19th May at Blean Woods but they were first seen as early as 6th May in Devon.

Glanville. Photo by Nigel Jones

34 Fritillaries (Nymphalidae) BUTTERFLY ABUNDANCE IN 2011

Speckled Wood (Pararge aegeria) Wall Brown (Lasiommata megera)

No. years with 36 2011 Rank: 4 No. years with 36 2011 Rank: 35 Collated Index: Collated Index: Change in Collated Index 12 Long-term 145*** Change in Collated Index -20 Long-term -83*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 11-July Series mean 27-July Mean flight date 2011: 08-July Series mean 28-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G G G G G G G G Collated Index Collated Index G G G 10 10 G log log 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Speckled Wood annual abundance increased by 12%, It was another poor year for the Wall Brown, with continuing the run of good years over the last decade, annual abundance down by 20%. There hasn’t been a with the 2011 index being the fourth best in the series. run of good years since the late 1980s, and 2011 was the The largest annual increases included from 66 in 2010 to second worst year on record. 202 in 2011 at Cavenham Heath in Suffolk and from 54 to 162 at Moors Valley in Dorset. The only three-figure index was 133 at Dodman in Cornwall. The butterfly had a poor year at many sites, The largest site index was 577 at Pamber Forest in including Hucker’s Bow, Sand Point in Avon and Hampshire, though this value was somewhat lower than Southfield Hog Cliff in Dorset where, at each, none the 915 recorded in 2010. The highest day count was 88 were seen in 2011 despite double figure indices in 2010. on 30th July at Itchen Valley Country Park (3 Copses) in Hampshire. Over the long-term, Speckled Wood Sites which bucked the trend included Bury Ditches in abundance has increased significantly across the UK by Shropshire where the index went from 1 in 2010 to 42 in almost 150%. The mean flight date was more than two 2011. weeks earlier than the series average. The Wall Brown has significantly declined by more than 80% since 1976 on monitored sites and has been lost from a lot of inland sites as its range in southern Britain has become increasingly restricted to the coast.

The mean flight date was 20 days earlier than the long- term average.

Browns (Satyridae) 35 BUTTERFLY ABUNDANCE IN 2011

coverage, especially given that the number of monitored Mountain Ringlet (Erebia epiphron ) sites producing indices has waned from a series high of 20 sites in 2005 to just six in 2011. The Scotch Argus The Mountain Ringlet is our rarest resident brown, being was one of the very few species to show a later flight restricted to high altitude grassland habitats in Scotland period in 2011 than the series average, presumably a and northern England. This is a species for which we lack result of the poor weather during the flight period of this consistent data on any site, let alone across a number of late summer species. sites, due to the difficulties of walking transects imposed by the changeable weather in such remote habitats. Thus, site indices are rarely produced. Monitoring of this species has been carried out since 1977 at Ben Lawers (Tayside) and counts were considerably higher in 2011 than in 2010. However, at the only other site with a good run of annual counts, Glasdrum (Argyllshire), numbers were down in 2011 compared with 2010, but were the second highest on record for this site since 2002. Improving the coverage of this rare and threatened species is a difficult task, but will enable us to determine more accurately its population status.

Scotch Argus (Erebia aethiops) Scotch Argus. Photo by Tim Melling No. years with 33 2011 Rank: 14 Collated Index: Change in Collated Index 10 Long-term 136** Marbled White (Melanargia galathea) 2010-11 (%): trend (%): Mean flight date 2011: 13-Aug Series mean 10-Aug No. years with 36 2011 Rank: 20 flight date: Collated Index: Change in Collated Index 18 Long-term 53 Collated Index plot: 2010-11 (%): trend (%): Mean flight date 2011: 04-July Series mean 15-July flight date:

Collated Index plot: G G G G G G G G G G G G G G G G G G G G G G GG G G G G G G G Collated Index G G G 10 G G G G G G G G G G G G G G G G G G G G log G G G G G G G G G G G G G 1.0 1.5 2.0 2.5 3.0 G

Collated Index G

1976 1981 1986 1991 1996 2001 2006 2011 10

Year log 1.0 1.5 2.0 2.5 3.0 For the last three years there has been little change in 1976 1981 1986 1991 1996 2001 2006 2011 Scotch Argus abundance, with a modest increase of 10% Year detected in 2011. The largest site index was 1,294 at Glasdrum in Strathclyde where there were four Marbled White abundance increased by a fifth in 2011, consecutive three-figure counts between 8th August and with the year classed as being at or just below average 1st September. Four other sites recorded three-figure for the series. Three-figure indices were recorded at 96 indices, with the largest increase being from 275 in 2010 sites, the largest of which was 2,275 at Whippingham to 515 in 2011 at Arnside Knott in Cumbria. (fields) on the Isle of Wight, over 800 more than 2010 at the same site and more than double the next highest There has been a significant increase in Scotch Argus index of 839 recorded at West Sedgemoor in Somerset. abundance at monitored sites, although the species This was the fourth highest index on record with a peak range is undersampled in Scotland so the trend may not count of 803 on 1st July. Five sites recorded the be fully representative. There is a need to boost sample butterfly for the first time in 2011.

36 Browns (Satyridae) BUTTERFLY ABUNDANCE IN 2011

The Marbled White abundance trend is classed as showing little or no overall change across the UK since Marbled White site trends 1976-2011 1976, though there have been several periods of change. Marbled White site !( Declining trends 1976-2011 !( Increasing In the late 1970s and early 1980s there was a large !( increase coinciding with a range expansion. !( Stable !( !( !( !( !( !( !( !( !(!( !( !( There was then a substantial decline over a four-year !( !( !( !( !(!( !( !(!( !( !( !( !(!( !(!(!( !( !( !(!(!( !( !( period during which numbers dropped to the 1976 base !(!( !(!(!( !(!( !( !( !( !(!( !( !( !( !( !( !(!( year level. This was followed by another period of !( !( !( !(!( !( !( !( !(!(!(!(!( !( !( !(!( !(!( !( !(!( !( !( !( !( !( !( !( !( !( !( !( increase after which the population has remained !(!( !( !(!(!( !( !(!( !( !(!( !(!(!( !(!(!( !(!(!(!(!(!( !(!(!(!( !( !(!( !( !( !(!( !( !( !(!(!( !( !( !(!(!( !( relatively stable with small, regular annual fluctuations. !( !(!(!( !(!( !(!(!(!( !( !(!( !( !( !( !(!(!( !(!(!( !( !( !(!( !( !( !( A plot of site trends is given in Figure 13. This shows that the majority (>50%) of site trends are classed as stable (no overall change), whilst there are Figure 13. Long-term site trends for Marbled White since 1976 proportionately more increasing sites in south-east on sites with sufficient data. England and at the northern range margin, and proportionately more decreasing sites in central- southern and south-western areas. Grayling (Hipparchia semele)

In 2011, the mean flight date was advanced by 10 days. No. years with 36 2011 Rank: 28 Collated Index: Change in Collated Index -38 Long-term -59*** 2010-11 (%): trend (%): Mean flight date 2011: 02-Aug Series mean 05-Aug flight date:

Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G

Collated Index G 10 log 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 Year

It was a poor year for Grayling, the ninth worst in the series, with annual abundance reduced by more than a third. Substantial declines included from 372 in 2010 to 98 in 2011 at North Warren in Suffolk and from 172 to 96 at Upton Heath North in Dorset.

There were nine indices which reached three-figures, Marbled White. Photo by Tony Cox the highest being 244 at Arnside Knott (National Trust) in Cumbria. The highest day count was 133 on 3rd July at the Great Orme Country Park in Gwynedd. Just to demonstrate how variable trends can be across sites, there was a spectacular increase at Crook Peak in Somerset, with an index of 140 in 2011 compared with eight in 2010. Grayling has declined significantly in abundance across the UK by almost 60% since 1976.

Browns (Satyridae) 37 BUTTERFLY ABUNDANCE IN 2011

Meadow Brown abundance was up by 28% in 2011, Gatekeeper (Pyronia tithonus) though it was still a below average year, ranked 26 out

No. years with 36 2011 Rank: 33 of 36. Noteworthy increases included from 289 in 2010 Collated Index: to 1,092 in 2011 at Winspit Valley in Dorset and from Change in Collated Index -13 Long-term -30 747 to 2,201 at Swan Barn Farm in Surrey. The largest 2010-11 (%): trend (%): index was an impressive 11,604 at Whippingham fields Mean flight date 2011: 01-Aug Series mean 02-Aug on the Isle of Wight, this being the fourth highest on flight date: record and the highest since 2003. Collated Index plot: Sites which had a poor year with annual abundance decreasing by more than 80% included Breadsall Cutting in Derbyshire and the Gulley & Walcombe

G G Slade in Somerset. G GG G G G G G G G G G G G G G G G G G G G G G G G G G G G G G The long-term trend across monitored sites is classed as G G

Collated Index showing little or no overall change, with annual 10 fluctuations small comparative to many other UK log butterflies. The mean flight date was close to the series 1.0 1.5 2.0 2.5 3.0 average. 1976 1981 1986 1991 1996 2001 2006 2011 Year Small Heath (Coenonympha pamphilus)

For the fifth year in a row Gatekeeper abundance was No. years with 36 2011 Rank: 17 well below the series average, with 2011 ranking as the Collated Index: fourth worst year since the start of monitoring. Across Change in Collated Index 5 Long-term -55** all sites, abundance was reduced by 13% between 2010 2010-11 (%): trend (%): and 2011, though some sites fared substantially worse. Mean flight date 2011: 07-July Series mean 09-July flight date: At Fairmead in Essex there was a drop from 461 in 2010 to 114 in 2011 and at Hatfield Forest from 280 to 46. Collated Index plot: Four-figure indices were recorded at five sites, the maximum being 2,366 at Whippingham fields on the Isle of Wight. The long-term trend for Gatekeeper G shows little or no overall change. The mean flight date G G G G GG G G G G G G G G G in 2011 was very similar to the series average. G G G G G G G G G G G G G G G G G G G G Collated Index

Meadow Brown (Maniola jurtina) 10 log No. years with 36 2011 Rank: 26 1.0 1.5 2.0 2.5 3.0 Collated Index: 1976 1981 1986 1991 1996 2001 2006 2011 Change in Collated Index 28 Long-term 4 2010-11 (%): trend (%): Year Mean flight date 2011: 18-July Series mean 21-July flight date: Following an improved year in 2010, Small Heath

Collated Index plot: received a further boost in 2011 with a modest 5% increase in abundance detected. Increases included from 360 in 2010 to 927 in 2011 at Frog Firle Farm in East Sussex and from 382 to 744 at Kingley Vale in West Sussex. The largest index of 1,820 was recorded at G G G G G G G G G G G Friston Hill in Sussex, this being the fifth highest index G G G GG G G G G G G G GGG G G G G G G G G G G on record for this butterfly. The Small Heath fluctuates

Collated Index considerably from year to year, though there has been a

10 significant decline in abundance of more than 50% over

log the long-term. The available data suggests the butterfly

1.0 1.5 2.0 2.5 3.0 is doing better in Wales and Scotland than in England. 1976 1981 1986 1991 1996 2001 2006 2011 The mean flight date in 2011 was around the series Year average.

38 Browns (Satyridae) BUTTERFLY ABUNDANCE IN 2011

Large Heath (Coenonympha tullia) Ringlet (Aphantopus hyperantus)

No. years with 22 2011 Rank: 1 No. years with 36 2011 Rank: 4 Collated Index: Collated Index: Change in Collated Index 12 Long-term 362*** Change in Collated Index -13 Long-term 334*** 2010-11 (%): trend (%): 2010-11 (%): trend (%): Mean flight date 2011: 05-July Series mean 09-July Mean flight date 2011: 06-July Series mean 15-July flight date: flight date:

Collated Index plot: Collated Index plot:

G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G

Collated Index G G Collated Index G G 10 10 G

log log G 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0

1976 1981 1986 1991 1996 2001 2006 2011 1976 1981 1986 1991 1996 2001 2006 2011 Year Year

Although annual abundance was up by only 12%, Large For the second year in succession Ringlet abundance Heath produced its highest index of the 22-year series. was down, with a 13% reduction from 2010. However, The largest increase was at Meathop Moss in Cumbria it was still a well above average year – the fourth best in where there was a rise from 605 in 2010 to789 (a series the series. Sharp declines included from 238 in 2010 to high) in 2011. 32 in 2011 at Friargate Station in Derbyshire, from 750 to 193 at Blunts Wood & Paiges Meadow in East Sussex Cors Fochno in Ceredigion produced the highest Welsh and from 695 to 202 at Carrinton’s New Farm in index of 136, whilst Knowetop Lochs in Dumfries and Buckinghamshire. The largest substantial increase was Galloway topped the Scottish sites with 41. The peak from 44 to 188 at Craigavon Lakes in Armagh, Northern day count, not too surprisingly, was recorded at Ireland. The largest site indices were 1,362 at Bradfield Meathop Moss with an impressive 529 on 28th June. Woods in Suffolk and 1,005 at Wyre Forest West in Hereford and Worcester. In 8 of the last 10 years Large Heath has produced above average indices and there has been a significant increase The Ringlet has increased significantly by more than in abundance of more than 350% over the series. 300% since 1976, though much of this increase was in However, with relatively few monitored sites (11 over the earlier years of the scheme and the population on the series) these results should be treated with caution, monitored sites has since stabilised. Frequenting as they may not fully reflect the national picture. damper grassland habitats than some of the other browns on the wing at the same time, one might expect The mean flight date in 2011 was within four days of the the Ringlet to have not declined in this recent run of long-term average. wetter late-summers. However, temperatures were also down in July 2011 and the exceedingly dry spring may have had a deleterious effect on larval survival.

Ringlet was out exceptionally early in 2011 with transect records as early as 21st April in Northern Ireland at Breen Oakwood in Antrim and on 22nd April at Scadbury Park in Kent. However, these were two standout records with no more seen until 19th May and the mean flight date was just a week and a half earlier than the series average.

Browns (Satyridae) 39 UKBMS NEWS

Online Data Entry for Transect Walkers A new way of analysing UKBMS data Last year we reported that online recording for the Emily Dennis, Steve Freeman, Tom Brereton, UKBMS was under development, and work on this David Roy feature has been progressing well. A test version has been We have been developing a new statistical method for examined by UKBMS staff and will receive further analysing UKBMS data to make more efficient use of testing from a group of volunteers over the 2012/13 this fantastic dataset. Our existing methods are winter. We are now confident that this feature will be up relatively inefficient at taking account of gaps in and running for any volunteers who wish to use it during recording, for example, when there are unsuitable the 2013 season. weather conditions. On average across the whole UKBMS dataset, 38% of visits are missed, with a higher With the current version of Transect Walker (TW2.5) proportion of weeks missed at the beginning and end of now seven years old, it is becoming rather out-dated and the season and a higher proportion missing from seems to pose new problems each time a new Windows northerly versus southerly sites. operating system is released. Using an online system means that recorders are no longer required to install or We are currently testing a new analytical approach operate proprietary software. You will just need access to which uses all data in the calculation of national and the internet and your own login details. regional indices of butterfly populations (e.g. Log Collated Index plots over time). The method estimates The online system will help us to speed up data capture the seasonal pattern (flight period) for each species each each year, as recorders will be entering their data directly year (and for different geographic regions), to enable us onto a central database, rather than the current stand- to estimate missing counts. We then combine the alone version of Transect Walker which needs to be estimated and observed counts, and correct for different packaged and distributed at the end of each season. Many sites recorded in different years, to calculate a national of the key features from Transect Walker will be carried or regional index of abundance. over to the new system, with annual charts and plots available. Compared to the existing approach, we have found that the new method provides more accurate and powerful One key advantage is that you will not need to wait to the estimates of trends over time in butterfly populations. end of the season before you submit data, as you will now In addition, the new method allows all volunteer records be able to do so, on a weekly basis. This also means that to contribute to the indices and thus incorporates data you will be able to see a summary of other transect data from more sites within the geographic range of species. being entered week-by-week across the UK. On average, the new model enables 60 extra sites per County/Branch Co-ordinators will still have a very species (range = 1 to 126 sites) to be included within important role to play, and they will be able to access and calculations of national indices. We are currently examine all data from their area as it is submitted. finalising the description of the new method for publication and automating the new method within the Transect Walker has served us very well for more than a data processing routines for the UKBMS. We aim to decade and we will still be able to receive data in that adopt the new analysis approach for reporting of 2012 format if preferred. However, we do see the online UKBMS data, alongside a full comparison between the development as a big step forward and will be sending current and new method to be included in next year’s out further details to recorders in good time for you to set report to recorders. We also aim to use the new method up your accounts prior to the 2013 season. to incorporate data from the Wider Countryside Butterfly Survey within national and regional indices.

40 FEATURES

The Wider Countryside Butterfly Survey in 2011 Zoë Randle, Tom Brereton, Kate Riseley & David Roy Introduction In 2011 the Wider Countryside Butterfly Survey (WCBS) ran for a third successful year. Resources were at similar levels to previous years in England, Wales and Northern Ireland, though thanks to additional funding from Scottish Natural Heritage coverage was boosted considerably in Scotland. In total, 523 recorders made 1,467 visits to 723 squares, walking almost 3,000km of survey line and counting 67,570 butterflies of 45 species. There was a welcome 4% increase in the number of squares sampled from 693 in 2010 to 723 in 2011. However, there remained a 5% reduction in squares covered compared to 2009, the year the WCBS was launched.

Scheme organisation and participation The WCBS runs as a partnership between Butterfly Conservation (BC), the British Trust for Ornithology (BTO) and the Centre for Ecology & Hydrology (CEH). Participants include recorders from the Figure 14. Location of the WCBS squares covered by BC (pink BTO/JNCC/RSPB Breeding Bird Survey (BBS) and BC circles), BTO (blue) and contract (yellow). volunteers. BC recorders were co-ordinated at the local level within BC branches through a network of WCBS We now have five years of WCBS data (if the pilot years Champions. National co-ordination was undertaken by of 2007 and 2008 are included) meaning that the time Zoë Randle for BC with support for BBS recorders series of repeat samples squares is developing well, with provided by Kate Risely at BTO HQ. 404 squares sampled in each of the three years of the survey and 78 squares with a five-year data run Survey coverage comprised 276 BBS squares sampled by (including pilot surveys). In 2011, 172 new squares BTO recorders, 362 squares sampled by BC recorders and were established, 13% by BTO recorders, 38% by BC a further 85 squares sampled by nine contractors in recorders and 49% by contractors in Scotland. During Scotland (Figure 14). BC coverage increased by 2% over the core July to August survey period 1,306 surveys the previous year, whereas BTO fell by 16%. Lack of were completed, with 77% of squares (559 in total) promotion and uncertainty over the future of the scheme receiving the required two visits (4% fewer than in were likely to have contributed to this reduction. The 2010). Additional visits to squares included 135 in weather may also have been a factor: the Met Office spring, 25 in September and 188 over the core period. reported that summer 2011 was the coolest since 1993 and Optional spring visits again proved valuable, providing that summer rainfall was 18% above the norm, leading to records for species with spring flight periods. For many days that were unsuitable for butterfly recording. example, Orange-tip was recorded in 32 squares.

The best BC Branch coverage (excluding any additional The majority of recorders (82%) surveyed single BBS squares) was achieved in Dorset and Norfolk with squares, the maximum being six by Dave Ayling in each covering 32 squares; Sussex came in second with Somerset. The most visits to a single square was seven 26 squares surveyed and Gloucestershire third with 22. (one more than last year) made by David Warren in BTO BBS square coverage was greatest in Sussex and Radnorshire, Wales. The busiest survey day was Yorkshire (21 squares each), Kent (18), Upper Thames Monday 22nd August when 51 visits were made (3.4% (18), South Wales (16) and West Midlands (16). The of the year total), followed by Saturday 23rd July, with biggest increase in coverage was in Scotland with 73 48 visits. Data quality and recording standards were more squares being surveyed than in 2010. However, in considered high again, with less than 0.01% of the Scotland there are still large gaps in coverage. Scotland records being obvious misidentifications, based on extends over ca. 32% of the UK land surface, yet species known flight times and distributions. Efficiency accounted for only 17% of squares sampled, so ideally a in data collation was slightly up on 2010, with 82% of doubling of effort is needed to eliminate the under data being entered online (80% in 2010, 70% in 2009). sampling bias.

41 FEATURES

for the third year in a row with 9736 individuals counted, and the most widespread species for the second successive year, being found in over 80% of squares. Once again, a small suite of species accounted for the majority of individuals counted: Meadow Brown, Small White, Green-veined White, Large White and Gatekeeper comprised 63% of all butterflies seen (Table 3). It was an improved year for the Red Admiral, rising five places to become the 6th most frequently encountered butterfly.

A similar increase was mirrored in Butterfly Conservation’s Big Butterfly Count www.bigbutterflycount.org where the Red Admiral rose from being the eighth most abundant species in 2010 to the fifth most abundant in 2011 and in the Garden Butterfly Survey (recorded in 91% of gardens in Red Admiral. Photo by John Money 2010 and 96% in 2011).

Butterfly sightings Scotch Argus attained a higher (and likely more More than three-quarters of the UK’s regularly representative) UK ranking, rising 11 places to become occurring butterfly species were recorded, with the total the eleventh most abundant species due to the coverage of 45 being one fewer than in 2010 and two fewer than boost in Scotland. This butterfly was twice as abundant in 2009. Swallowtail and Silver-spotted Skipper were as Meadow Brown in squares where both species recorded for the first time in the survey, whilst absences occurred. A better year was had by two of the ‘golden included Grizzled Skipper, Marsh Fritillary, Purple skippers’, for example, Essex Skipper was up six places Emperor and Wood White. Twenty-five species were in rank occupancy and five places in abundance. Both recorded in 30 or more squares (the same number as in Small Tortoiseshell and Common Blue fared poorly in 2010), whilst 17 of these were recorded in more than 2011, the latter being found in only a third of squares 100 squares (see Table 3). compared to 56% in 2010. The WCBS once again showed the current scarcity of the Small Tortoiseshell, The WCBS continues to contribute data to the with, on average, less than one likely to be seen per Butterflies for the New Millennium (BNM) database, kilometre walked in the general countryside. with 44 new 10km square records generated for 19 species. Discoveries included new 10km records for Grayling in the Scottish Borders and Dumfries and Galloway and Dark Green Fritillary in Aberdeenshire, Argyll and Bute, Cambridgeshire, North Lanarkshire and West Lothian.

Comparisons with previous years On average, recorders counted 47 butterflies of seven species per survey made over the July and August period. These figures represent a 22% reduction in numbers from 2010 and an alarming 41% from 2009, when recorders saw an average of 80 butterflies.

The figures from the WCBS concur with those from

UKBMS transect sites and indicate that it was another Wall Brown Photo by Peter Eeles relatively poor year for common and widespread butterflies. Species richness per survey was the same as For a third consecutive year Wall Brown declined in 2010, but one fewer than in 2009. distribution and for the first time was found in less than 10% of squares, qualifying it to be about as widespread The majority of wider countryside species were ‘non- as Silver-washed Fritillary and less so than Brown movers’ having a similar distribution and abundance Argus. Figure 15 shows the distribution of Wall Brown ranking in 2011 to what they had in 2010. In July and and its associated change in abundance in WCBS squares August, Meadow Brown was the most abundant species for which there are two or more years of data. This

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Table 3. Occurrence and abundance data for butterflies recorded during repeat summer visits to 559 WCBS squares

Species Occupancy Abundance

No. 2011 % 2011 Rank 2011 Total counted 2011 % of all 2011 Rank Squares (2010) (2010) counted (2010) (2010 Rank)

Meadow Brown 454 81.2 (81.3) 1 (1) 9736 18.4 (17.0) 1 (1) Small White 426 76.2 (80.6) 2 (2) 8113 15.4 (16.2) 2 (2) Green-veined White 409 73.2 (69.6) 3 (5) 4817 9.1 (9.0) 5 (6) Large White 408 73.0 (79.6) 4 (3) 4411 8.4 (9.4) 6 (5) Gatekeeper 386 69.1 (71.9) 5 (4) 6408 12.1 (13.7) 3 (3) Red Admiral 368 65.8 (46.1) 6 (11) 1488 2.8 (1.2) 9 (11) Speckled Wood 332 59.4 (63.1) 7 (6) 2736 5.2 (3.7) 7 (8) Small Tortoiseshell 297 53.1 (56.8) 8 (7) 1884 3.6 (3.0) 8 (9) Ringlet 275 49.2 (53.7) 9 (9) 5016 9.5 (9.4) 4 (4) Peacock 266 47.6 (53.6) 10 (10) 1066 2.0 (2.2) 12 (10) Comma 203 36.3 (45.7) 11 (12) 424 0.8 (1.0) 16 (13) Common Blue 186 33.3 (56.0) 12 (8) 748 1.4 (5.2) 13 (7) Small Skipper 140 25.0 (21.6) 13 (15) 1109 2.1 (1.2) 10 (12) Holly Blue 124 22.2 (28.4) 14 (14) 314 0.6 (0.6) 19 (18) Small Copper 121 21.6 (33.7) 15 (13) 310 0.6 (0.9) 20 (14) Small Heath 99 17.7 (15.1) 16 (18) 632 1.2 (0.8) 14 (15) Large Skipper 96 17.2 (19.2) 17 (16) 325 0.6 (0.7) 18 (17) Small/Essex Skipper 62 11.1 (12.6) 18 (20) 355 0.7 (0.8) 17 (16) Essex Skipper 59 10.5 (7.3) 19 (25) 287 0.5 (0.2) 21 (26) Brimstone 53 9.5 (16.5) 20 (17) 109 0.2 (0.3) 26 (24) Brown Argus 52 9.3 (13.4) 21 (19) 161 0.3 (0.6) 23 (19) Marbled White 48 8.6 (11.4) 22 (21) 538 1.0 (0.6) 15 (20) Wall Brown 41 7.3 (9.0) 23 (23) 158 0.3 (0.4) 24 (23) Silver-washed Fritillary 40 7.2 (8.0) 24 (24) 142 0.3 (0.5) 25 (21) Painted Lady 35 6.3 (10.5) 25 (22) 56 0.1 (0.2) 30 (27) Purple Hairstreak 26 4.7 (3.7) 26 (26) 71 0.1 (0.1) 28 (30) Scotch Argus 26 4.7 (1.4) 26 (31) 1068 2.0 (0.4) 11 (22) Dark Green Fritillary 23 4.1 (2.4) 28 (27) 70 0.1 (0.1) 29 (33) Grayling 13 2.3 (2.0) 29 (29) 164 0.3 (0.2) 22 (25) Small Pearl-bordered Fritillary 13 2.3 (0.9) 29 (32) 78 0.1 (0.1) 27 (34) White Admiral 8 1.4 (2.2) 31 (28) 9 0.0 (0.1) 35 (29) Clouded Yellow 5 0.9 (1.5) 32 (30) 48 0.1 (0.1) 31 (28) Chalk-hill Blue 4 0.7 (0.7) 33 (33) 13 0.0 (0.1) 34 (32) Green Hairstreak 3 0.5 (0.3) 34 (-) 5 0.0 (-) 36 (-) Orange-tip 3 0.5 (0.7) 34 (33) 6 0.0 (0.03) 37 (35) Large Heath 2 0.4 (0.3) 36 (37) 34 0.1 (<0.01) 32 (39) Lulworth Skipper 2 0.4 (0.2) 36 (38) 29 0.1 (0.02) 33 (36) Northern Brown Argus 1 0.2 (-) 38 (-) 3 0.0 (-) 38 (-) Silver-studded Blue 1 0.2 (-) 38 (-) 1 <0.01 (-) 39 (-) Brown Hairstreak 1 0.2 (0.7) 38 (33) 1 <0.01 (0.01) 40 (37) White-letter Hairstreak 1 0.2 (0.7) 38 (33) 2 <0.01 (0.01) 40 (38) Dingy Skipper 1 0.2 (0.2) 38 (38) 1 <0.01 (<0.01) 40 (42) Small Blue 1 0.2 (0.2) 38 (38) 1 <0.01 (<0.01) 40 (41) Pearl-bordered Fritillary 0 - (-) - (-) - - (-) - (-) Purple Emperor 0 - (-) - (-) - - (-) - (-) Adonis Blue 0 - (0.2) - (38) - - (0.08) - (31) Wood White 0 - (0.2) - (38) - - (<0.01) - (39)

43 FEATURES

confirms (as documented through BNM distribution Silver Y was the most widespread species, with 63 surveys) that the butterfly is now highly localised in individuals counted in 40 squares. However, occupancy inland areas of Central and Southern England, and also and abundance of this species declined by 53% and 76% shows that the pattern of increases and decreases across respectively from 2010 levels. The Six-spot Burnet was the UK in recent years is highly mixed. In squares where the most abundant species with 133 individuals counted the butterfly was seen, the average number of individuals in 27 squares. In spite of this, as with the Silver Y, counted fell by a third (5.7 in 2009 to 3.8 in 2011), abundance of Six-spot Burnet fell by 30% compared to compared with a 35% decline on UKBMS monitored 2010. Occupancy and abundance of the remaining eight sites over the same period. Occupancy also fell - Wall most frequent and abundant moths is given in Table 4. Brown occurred in 46 squares in 2009 (6%) and 30 squares in 2011 (4%). The BC National Garden Butterfly Species Squares Total counted Survey also showed that the number of gardens where Wall Brown was present fell by 33% from 2009 to 2011. Moths Silver Y 40 63

Six-spot Burnet 27 133

Yellow Shell 19 34

Common Carpet 16 35

Cinnabar 15 112

Humming-bird Hawk-moth 13 19

Shaded Broad-bar 12 19

Chimney Sweeper 11 92

Silver-ground Carpet 9 23

Narrow-bordered five-spot Burnet 6 43

Dragonflies

Common Darter 56 249

Brown Hawker 52 94

Southern Hawker 41 77

Common Blue Damselfly 38 207

Banded Demoiselle 27 163

Golden-ringed Dragonfly 25 44

Migrant Hawker 22 72

Emperor Dragonfly 21 35

Common Hawker 13 34

Azure Damselfly 10 126

Table 4. Top ten most widespread and abundant day-flying moths and dragonflies

Figure 15. Distribution and abundance change of the Wall Brown on WCBS squares (with two more years of data 2009- There were 25 species of dragonfly recorded, with 1,598 2011). Black circles (increase), red circles (decrease), yellow individuals counted across 222 squares (115 BTO, 95 circles (no change), blue circles (not seen). BC, 12 contract). Dragonfly numbers were down by 50% compared with 2010, with recording in 40 fewer Other Insects squares. The Common Darter was the most widespread Moth records were collected across 146 squares, with species for the third year running, being detected in 25% 754 individuals counted (52% fewer than in 2010) of 41 of squares with dragonfly records (the same level as in species (three less than in 2010). These figures were all 2010). This was also the most abundant species, down on 2010 levels, with recording in 26% fewer replacing the Common Blue which held this position in squares, 52% fewer moths counted and with three less 2009 and 2010. species. It was a good year for the Migrant Hawker, with On average five moths per square were seen in 2011 abundance up on 2010 levels. compared to eight in 2011, representing a reduction in mean species richness of 38%. On the positive side, 40 new 10km square records were generated. The migrant

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The initial transect, known as ‘Magdalen Hill Down (original)’ was set up in 1990, when Butterfly Conservation began to manage what had become a heavily scrubbed-over piece of south-facing chalk downland. Despite the scrub, the site retained small populations of many chalk grassland butterflies in sheltered pockets. With appropriate conservation management, many of these species have since shown dramatic increases.

Common Darter Photo by Stephen Burch The original area of downland extending over nine (www.stephenburch.com) hectares was added to in 1996, when an opportunity arose to acquire an adjacent field to the east. This site, Future plans known as ‘Magdalen Hill Down (extension), added a The WCBS will be organised in the same way for at further 13 hectares to the reserve. With the exception of least the next two years, with Zoë Randle co-ordinating a tiny fragment of unimproved chalk grassland in the the scheme for Butterfly Conservation. We hope to south-west corner, this new addition was an arable field. recruit more volunteers to continue to grow the scheme. With Heritage Lottery funding it was transformed in Please contact Zoë at Butterfly Conservation if you 1997 by re-seeding with a local provenance chalk would like to take part. grassland mix. Although still a long way from chalk downland, it has since then become high quality butterfly habitat. Magdalen Hill Down – restoring butterfly populations over the long-term Dr Andy Barker Situated in central Hampshire, Butterfly Conservation's Magdalen Hill Down (MHD) Reserve, near Winchester, is one of the top chalk grassland sites in the county. It records around 30 butterfly species annually and, with others turning up as strays, the overall tally for the site exceeds 35 species. The reserve can be considered in three parts, each of which has a butterfly transect. These transects are organised on a rota basis involving five people per site. This seems to work well, producing consistent data, and few missed weeks (usually 24+ weeks covered annually). This article summarises the history of the site, its monitoring, and some of the noteworthy trends.

Chalkhill Blue Photo by Keith Warmington

The most recent acquisition is a 23 hectare area known as ‘Magdalen Hill Down (north)’. This, another former arable field, came under the management of Butterfly Conservation in 2004, when it too was re-seeded. It adjoins both the ‘original’ and ‘extension’, to make a nature reserve of 45 hectares (110 acres), 36 hectares of which is arable reversion, and nine hectares of restored downland. All sites are managed by cattle and sheep grazing, with varying levels of rabbit activity, especially on MHD original. Some of the key results from the butterfly transect monitoring will now be considered.

High quality chalk grassland at Magdalen Hill Down (original)

45 FEATURES

Rise of the Chalkhill Blue (Polyommatus coridon) Return of Grizzled Skippers Since scrub clearance in the early 1990s, and subsequent One of the most amazing stories since butterfly transect introduction of cattle and sheep grazing, the chalk monitoring began at Magdalen Hill Down has got to be grassland condition at MHD ‘original’ has improved the return of the Grizzled Skippers to MHD ‘original’. considerably. This has resulted in a 10-fold increase in It was extremely rare to see the butterfly on the site numbers of Chalkhill Blues. It showed a rapid year on during the 1990s, with annual indices of zero in all bar year rise from an Annual Index of 317 in 1991 to 1,345 four of the first 15 years (Figure 17). Only 1994 (1), in 1996 at a time when many sites were declining 1996 (1), 1997 (2) and 2002 (2) produced any Grizzled (Figure 16). Since then the Annual index has always Skippers. Imagine the surprise of the transect walkers, exceeded 1,000, peaking at 3,923 in 2010. when suddenly in 2005 the species turned up throughout the early part of the season to produce an Annual Index 4000 of 17. With the exception of a dip in 2008, the numbers average (Hants) Magdalen Hill Down have risen ever since, with 2011 producing a remarkable 3000 Annual Index of 82. Whether this is a natural

recolonisation or the recovery of a tiny population that 2000 was always present is not entirely clear, but whatever

Annual Index Annual the case, the site has now become one of the best sites in 1000 Hampshire for the species. It should be added that Dingy Skipper also occurs at the site and, despite all the

0

Bird’s-foot Trefoil, it has only been recorded on transect 2011 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 intermittently in 9 of the 22 transect years from 1990 to 2011, producing a maximum annual index of four. Even Figure 16. Annual changes in Chalkhill Blue abundance at Magdalen Hill Down Reserve compared with the average so, I remain convinced that it is only a matter of time across Hampshire before it too will undertake an expansion like the Grizzled Skipper has. Common Blue bonanza The Common Blue is one of Britain’s most widely Small Blues take off in 2011 distributed butterflies, yet to find sites where the The Small Blue is currently known from about 15-20 butterfly truly thrives is not as easy now as it used to be. sites in Hampshire, including a concentration of sites Fortunately, Magdalen Hill Down is one of those sites around Winchester. Despite locally frequent Kidney where the species does really well. Most encouraging of Vetch, Magdalen Hill Down ‘original’ has never all, it has established a major breeding population on produced many Small Blues on transect. The short turf MHD ‘extension’, which as mentioned previously, was and heavy rabbit grazing in the mid 1990s didn't really an arable field until 1996. From an Annual Index of 50 provide much suitable habitat, and half the transect in 1996, the re-seeded grassland mix, with lots of Bird's- years from 1990 to 2009 produced blanks. Other years foot Trefoil, clearly produced ideal habitat. By 1999 the recorded occasional individuals. Annual Index reached 575, and after, a decade producing indices averaging around 500, the 2010 By contrast, the re-seeded of MHD summer produced the remarkable Annual Index of ‘extension’ and more recently MHD ‘north’ have 1,507. In 2011, this figure crashed to a lowly 257, as provided transitional swards that are ideal for the indeed was the case throughout Hampshire, but the species. In each case it was found that Kidney Vetch, a long-term trend at the site is clearly upward. key species of the grassland mix, thrived in the early years, when the sward was open with a lot of bare earth. 100 As the sward matures, it tends to close in and Kidney

ż average (Hants) Ɣ Magdalen Hill Down Vetch does less well. To counteract this, bare earth 75 scrapes have been created, and flowering Kidney Vetch thrives in and around these. Populations are perhaps too

50 small to comment on trends, except to say that at MHD

Annual index Annual ‘north’, from an arable field with no Small Blues in

25 2004, single figure annual indices were produced from 2006-2009, then rising to 18 in 2010, and an impressive

0 48 in 2011. On this form, it now rates as one of the best

2011 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 sites in Hampshire. MHD ‘extension’ and MHD ‘original’ also produced double-figure annual indices in Figure 17. Annual changes in Grizzled Skipper abundance at 2011, with tallies of 14 and 11 respectively, making it the Magdalen Hill Down Reserve compared with the average across Hampshire best year for the species since transect recording began.

46 FEATURES

transect) up to 1998, but since then they have spread across the re-seeded grassland with numbers in Section 6 greatly reduced. On MHD ‘north’, Marbled White has shown an amazing rise in just seven years, with zero on transect in 2004, to a spectacular Annual Index of 623 in 2011. Clearly it likes the newly created habitat.

From 1996 to 2005, the Ringlet annual indices at MHD ‘extension’ fluctuated in the seven to 30 range before rising to approximately 60-70 over the period 2006- 2008, then more than 200 in each year since 2009, peaking at 272 in 2011. It is unclear to what extent this species breeds in the re-seeded area, but the population appears to be strengthening. The same pattern is also Restored grassland at Magdalen Hill Down, with abundant reflected at MHD ‘north’, rising steadily, year on year, Kidney Vetch from an Annual Index of seven in 2005 to 140 in 2011.

Satyrids respond well to re-seeded grassland Gatekeeper is seen with Meadow Brown at grassland Starting butterfly transects in year zero prior to arable sites throughout Hampshire, but their habitat needs are reversion to flower-rich grassland by re-seeding has clearly different. At both MHD ‘extension’ and MHD proved extremely interesting in understanding which ‘north’ it hasn't really taken to the re-seeded grasslands, species colonise the newly created habitat. The response but has simply shown fluctuating annual indices. The of Common Blue has already been described, but let us same is also true for the Small Heath, but given the now consider the Satyrids, some of which colonised negligible amounts of Sheep’s Fescue in the re-seeded very well, but others are still to get going. habitat it is perhaps not surprising, as this is the favoured larval foodplant. Nevertheless, Small Heath Magdalen Hill Down ‘original’ and the tiny remnant of did produce 2011 Annual Indices of 43 at MHD unimproved chalk grassland in one corner of MHD ‘extension’ and 48 at MHD ‘north’, which is fairly ‘extension’ had known populations of Meadow Brown, respectable given that the downland of MHD ‘original’ Gatekeeper, Ringlet, Marbled White and Small Heath only had an index of 93. prior to arable reversion, so which of these would colonise the re-seeded grasslands?

Undoubtedly the best coloniser has been the Meadow Brown, which on MHD ‘extension’ started with an Annual Index of 189 in 1996, but rose steadily to 1,083 in 2001, before fluctuating at around 1,000-1,200 since then, apart from a peak of 2,615 in 2004. The levelling- off may suggest that it has reached the carrying capacity of the habitat. Of the 10 main grasses present in the sward, Smooth Meadow Grass (Poa pratensis) is considered as the main species used by the Meadow Brown, even though it isn't the dominant grass (see Jeffreys & Barker, 2011 – available here http://www.hantsiow-butterflies.org.uk/conservation/ Marbled White Photo by Keith Warmington mhd%20botany.pdf). The more recently re-seeded MHD ‘north’ has also shown good colonisation by Hampshire's flagship Brown Argus site Meadow Brown, rising from an Annual Index of 55 in Magdalen Hill Down ‘original’ is probably the best 2005 to 730 in 2011, with further increases expected. Brown Argus site in Hampshire. However, it has to be said that the numbers of this species seen on transect Although showing a rapid initial response at MHD vary greatly from one year to the next. In 1990 an ‘extension’ from an Annual Index of 175 in 1996 to 430 Annual Index of 390 was recorded, but undoubtedly the in 1998, Marbled White numbers then fluctuated in the best years were in the mid-1990s, peaking with a 100-300 range before rising to 453 in 2011. massive Annual Index of 921 in 1995. At this time rabbit Interestingly, the individuals were largely concentrated pressure on the site was high and Common Rock-rose in the small area of remnant grassland (Section 6 of flourished in a short turf (5-8cm), open sward, with

47 FEATURES

plenty of bare earth. Since then rabbit pressure has eased documented in other publications, but is still worthy of considerably and, despite annual grazing with cattle and mention here, as it undoubtedly ranks as one of the sheep, a combination of warm wet summers and mild greatest butterfly events recorded on the Magdalen Hill winters has caused turf heights to rise to 10-15cm and Down butterfly transects. the sward to become tighter. This has caused Brown Argus Annual Indices to reduce to the 200-500 range, Final remarks which is still good, but not perhaps as good as it could Space does not permit a full account of all the other be. It should be pointed out, however, that Chalkhill species, but I should perhaps mention that Magdalen Blue has thrived under these slightly longer turf heights. Hill Down has a strong population of Green Hairstreaks, with Annual Indices on MHD ‘original’ ranging from 15-80, and peaking at 110 in 1996. Dark Green Fritillary and Duke of Burgundy are occasionally seen, and sometimes on transect, but are not currently regarded as breeding species at the site.

I have been fortunate enough to have been involved with Magdalen Hill Down and transect recording at the site since Butterfly Conservation started there in 1990. It is a truly inspirational site that has demonstrated what can be achieved with direct conservation action and long-term commitment, coupled with detailed monitoring.

Brown Argus Photo by Neil Hulme Some of the butterfly trends have been anticipated, some have been a complete surprise, and others have The Clouded Yellow years been truly spectacular, but above all it is a site that The 1990s saw a good run of Clouded Yellow years in through a combination of the efforts of professional staff Hampshire, with every even-numbered year being good, and volunteers has demonstrated butterfly populations and each odd-numbered year being poor. This was can recover and natural recolonisations are possible, reflected in the MHD ‘original’ transect annual indices, especially if the site is of a reasonable size and well but only 1996 (23) and 2000 (22) produced Annual managed. Indices of note. After a zero index in 2001, the period 2002-2006 was a remarkable period for Clouded Yellow, with each year producing a double-figure annual index.

The same pattern also occurred at MHD ‘extension’. Indeed, the re-seeded grassland, rich in Bird’s-foot Trefoil, proved ideal breeding habitat for the species, with a series high Annual Index of 69 in 2000. The last couple of years have been very poor, with none seen on any of the Magdalen Hill Down transects in 2011.

Painted Lady invasions There is no doubt that 1996 and 2009 were truly exceptional Painted Lady years, and south-facing chalk grassland sites like Magdalen Hill Down recorded very high numbers of this species, although depending on which day you did the transect at the key period made some difference. A typical year on the MHD ‘original’ transect produces a Painted Lady Annual Index of c.1-8, whereas in 1996 and 2009, the figures were 165 and 185 respectively. Even these seem fairly modest when compared with MHD ‘extension’, where values of 517 in 1996, and 1,940 in 2009 were achieved. This magnificent Painted Lady invasion has been well

48 CONTACTS

Contact details for local co-ordinators

RECORDING AREAS NAME & ADDRESS OF CO-ORDINATOR TELEPHONE EMAIL

Ian Middlebrook UK Butterfly Conservation, Manor Yard, East Lulworth, 01929 400209 [email protected] Wareham, Dorset, BH20 5QP.

SCOTLAND (overall) Vacant

Catherine Bertrand Butterfly Conservation, Slemish Complex, NORTHERN IRELAND 07584 597690 [email protected] Knockbracken Healthcare Park, Saintfield Road, Belfast, BT8 8BH

Clare Williams WALES (overall) Butterfly Conservation (Wales), 10 Calvert Terrace, 01792 642972 [email protected] Swansea, SA1 6AR

ISLE OF MAN Vacant

ENGLAND

Dave Wainwright NORTHERN ENGLAND Butterfly Conservation, Low Barns Visitor Centre, 01388 488428 [email protected] (Fritillaries) Witton-le-Wear, Bishop Auckland, DL14 0AG

Bedfordshire & Greg Herbert 01582 663784 Northamptonshire 3 Candale Close, Dunstable, Bedfordshire, LU6 3PE

Data co-ordinator Bedfordshire & Keith Balmer 01234 355435 [email protected] Northamptonshire 6 Salcombe Close, Bedford, Bedfordshire MK40 3BA

Louise Bacon Cambridgeshire [email protected] 236 Wimpole Road, Barton, Cambridge, CB23 7AE

Stu Burnet Cheshire & Peak District 17 Alderdale Road, Cheadle Hulme, Cheadle, 0161 485 5107 [email protected] Cheshire, SK8 5PP

Jim Barker Cornwall 01736 794134 [email protected] An Arth, Alexandra Road, St Ives, Cornwall, TR26 1BX

Cumbria Vacant

John Randall Devon 112 Peters Park Lane, St Budeaux, Plymouth, 01752 309857 [email protected] Devon, PL5 1PT

Bill Shreeves Dorset Little Garth, 5 Butt’s Mead, Shaftesbury, 01747 852587 [email protected] Dorset, SP7 8NS

Ken Orpe East Midlands 01332 730524 [email protected] 34 Derwent Avenue, Allestree, Derby, DE22 2DQ

Robert Smith Essex 165a Warley Hill, Great Warley, Brentwood, [email protected] Essex, CM13 3AG

Chris Wiltshire Gloucestershire The Brambles, Stinchcombe Hill, Dursley, 01453 545509 [email protected] Gloucestershire, GL11 6AQ

Andy Barker Hampshire & I.O.W. 13 Ashdown Close, Chandlers Ford, Eastleigh, 02380 270042 [email protected] Hants, SO53 5QF

Dr John Murray Field End, Marshalls Heath, Wheathampstead, 01582 833544 [email protected] Herts, AL4 8HS Herts & Middlesex

Andrew Wood 93 Bengeo Street, Hertford, SG14 3EZ 01992 503571 [email protected]

Kent Ade Jupp [email protected]

49 CONTACTS

RECORDING AREAS NAME & ADDRESS OF CO-ORDINATOR TELEPHONE EMAIL

Laura Sivell Lancashire 01524 69248 [email protected] 22 Beaumont Place, Lancaster, LA1 2EY

Robert Day Lincolnshire Little Holme Road, Walpole Cross Keys, King's Lynn, 01553 829077 [email protected] Norfolk, PE34 4EW

Norfolk Vacant

North East England Brian Denham 01325 263449 [email protected] (Durham & Northumberland) 1 Swaledale Avenue, Darlington, DL3 9AJ

Marjorie Brunt Somerset & Bristol Kea House, Chapel Lane, Butleigh, Glastonbury, 01458 850919 [email protected] Somerset BA6 8TB

Rob Parker Suffolk 01284 705476 [email protected] 66 Cornfield Road, Bury St Edmunds, Suffolk, IP33 3BN

Richard Donovan Surrey 0208 6441563 [email protected] 65 Stoughton Avenue, Cheam, Surrey SM3 8PH

Peter Atkinson Sussex 01903 690943 [email protected] 55 Furze Road, Worthing, W. Sussex, BN13 3BH

Upper Thames Mike Wilkins (Berks, Bucks & Oxon) 65, The Causeway, Steventon, Abingdon, 01235 831300 [email protected] Oxfordshire, OX13 6SE

Keith Warmington Warwickshire 30 New Street, Baddesley Ensor, Atherstone, 01827 715873 [email protected] Warwickshire, CV9 2DW

John Tilt West Midlands 01386 792458 [email protected] 9 Meadow Close, Flyford Flavell, Worcs., WR7 4DE

Geoff Hobson Wiltshire 01373 823820 [email protected] 30 Leigh Road, Westbury, Wiltshire, BA13 3QL

Jean Murray Yorkshire ‘High Up’, Binns Lane, Holmfirth, 01484 685286 [email protected] West Yorkshire, HD9 3BJ

WALES

Ceredigion Vacant

Denbigh, Flintshire & Vacant Wrexham

Glamorgan Vacant

Andrew Graham Gwynedd & Anglesey 01678 540370 [email protected] ‘Trawscoed’, Llanuwchllyn, Bala, Gwynedd, LL23 7TD

Monmouthshire Vacant

Montgomeryshire Vacant

Bob Haycock Pembrokeshire 01834 891667 [email protected] 1 Rushmoor Cottages, Martletwy, Narberth, SA67 8BB

Julian Jones Powys & Brecon Beacons Radnorshire Wildlife Trust, Warwick House, 01597 823298 [email protected] National Park High Street, Llandrindod Wells, Powys, LD1 6AG

50 CONTACTS

RECORDING AREAS NAME & ADDRESS OF CO-ORDINATOR TELEPHONE EMAIL

SCOTLAND

Neil Gregory Renfrewshire 01505 874 275 [email protected] 32 Oldhall Drive, Kilmacolm, Renfrewshire, PA13 4RF

Ayrshire Vacant

Borders Vacant

Dumfries & Galloway Andy Riches [email protected]

Nick Morgan East Lothian East Lothian Council, Landscape & Countryside 01620 827671 [email protected] Division, Block C, Haddington, East Lothian, EH41 3HA

Duncan Davidson Fife 01383 730 446 [email protected] 140 Pitcorthie Drive, Dunfermline, KY11 8BJ

Hilary Quick Scottish Orienteering Association, Highlands 01479 861374 [email protected] National Orienteering Centre, Glenmore Lodge, Aviemore, PH22 1QU

Louisa Maddison Lanarkshire Countryside & Greenspace Service, 01355 236 644 [email protected] Calderglen Country Park, East Kilbride, G75 0QZ

Stirlingshire, Argyllshire Andrew Masterman 0141 4231336 [email protected] & Bute Flat 1/3, 214 Calder Street, Glasgow, G42 7PE

References

Botham, M.S., Brereton, T.M., Middlebrook, Pollard, E., and Yates, T.J. (1993). Monitoring Butterflies for I., Cruikshanks, K.L. & Roy, D.B. (2008). United Kingdom Ecology and Conservation. Chapman and Hall, London. Butterfly Monitoring Scheme Annual report 2007. Centre for Ecology & Hydrology. Rothery, P., and Roy, D.B. (2001). Application of generalized additive models to butterfly transect count data. Journal of Fox, R., Warren, M.S., Brereton, T.M., Roy, D.B. & Applied Statistics 28:897-909. Robinson, A. (2011). A new Red List of British butterflies. Insect Conservation and Diversity 4: 159-172. Thomas, J., & Lewington, R. (2010). The Butterflies of Britain & Ireland. British Wildlife Publishing Ltd, Gillingham, Jeffreys, P. & Barker, A. (2011). Magdalen Hill Down Dorset. Extension: Review of botanical trends (1998 – 2010) and assessment of likely impact on selected butterfly species. Warren, M., Thomas, C.D., and Thomas, J.A. (1981). The Unpublished internal document Hampshire and Isle of Wight Heath Fritillary. Survey and conservation report. Unpublished Butterfly Conservation. report to the Joint Committee for the Conservation of British Insects. Butterfly Conservation, Wareham. Lewis, O.T., and Hurford, C. (1997). Assessing the status of the Marsh Fritillary (Eurodryas aurinia Rott.) – an example from Glamorgan (UK). Journal of Insect Conservation 1:159-161.

Pateman, R. M., Hill, J.K., Roy, D.B., Fox, R., & Thomas, C.D. (2012). Temperature-Dependent Alterations in Host Use Drive Rapid Range Expansion in a Butterfly. Science 336: 1028-1030.

51 APPENDICES

Appendix I

Appendix 1: Trends in UK BAP Priority species

Change in No. sites where No. sites where No. sites where Total sites BAP priority species Collated Index declining increasing stable recorded at 2010-11 (%)

Brown Hairstreak 3410 83 -27

Dingy Skipper 39 28 140 583 26

Duke of Burgundy 28 5 24 141 65

Glanville Fritillary 00113 129

Grayling 28 6 59 319 -38

Grizzled Skipper 30 21 104 437 96

Heath Fritillary 14 2 17 54 -5

High Brown Fritillary 16 5 40 126 0

Large Blue 14729 -21

Large Heath 12841 12

Lulworth Skipper 41122 84

Marsh Fritillary 18 9 49 222 -67

Northern Brown Argus 9119 70 21

Pearl-bordered Fritillary 29 6 44 225 103

Silver-studded Blue 5320 106 4

Small Blue 13 16 54 282 26

Small Heath 113 23 295 1250 5

Small Pearl-bordered Fritillary 27 14 61 291 17

Swallowtail 01011 41

Wall Brown 102 6 118 776 -20

White Admiral 20 17 83 333 -51

White-letter Hairstreak 8 5 19 246 -16

Wood White 8 1 12 84 -41

52 Appendix II

Vernacular & scientific names of butterfly species referred to in this report (vernacular names follow Emmet and Heath (1990) The Moths and Butterflies of Great Britain and Ireland Volume 7 Part 1, Harley Books, Colchester. The scientific names follow the Fauna Europaea website (version 2.2) www.faunaeir.org, accessed on 27-09-2010

Page no. for Common name Scientific name Authority species account

Adonis Blue Polyommatus bellargus (Rottemburg, 1775) 25

Black Hairstreak Satyrium pruni (Linnaeus, 1758) 21

Brimstone Gonepteryx rhamni (Linnaeus, 1758) 16

Brown Argus Aricia agestis Denis & Schiffermuller, 1775) 23

Brown Hairstreak Thecla betulae (Linnaeus, 1758) 19

Chalk-hill Blue Polyommatus coridon (Poda, 1761) 24

Chequered Skipper Carterocephalus palaemon (Pallas, 1771) 11

Clouded Yellow Colias croceus (Fourcroy, 1785) 16

Comma Polygonia c-album (Linnaeus, 1758) 30

Common Blue Polyommatus icarus (Rottemburg, 1775) 24

Cryptic Wood White Leptidea juvernica (Williams, 1946) 16

Dark Green Fritillary Argynnis aglaja (Linnaeus, 1758) 32

Dingy Skipper Erynnis tages (Linnaeus, 1758) 14

Duke of Burgundy Hamearis lucina (Linnaeus, 1758) 26

Essex Skipper Thymelicus lineola (Ochsenheimer, 1808) 12

Gatekeeper Pyronia tithonus (Linnaeus, 1767) 38

Glanville Fritillary Melitaea cinxia (Linnaeus, 1758) 34

Grayling Hipparchia semele (Linnaeus, 1758) 37

Green Hairstreak Callophrys rubi (Linnaeus, 1758) 19

Green-veined White Pieris napi (Linnaeus, 1758) 18

Grizzled Skipper Pyrgus malvae (Linnaeus, 1758) 14

Heath Fritillary Melitaea athalia (Rottemburg, 1775) 34

High Brown Fritillary Argynnis adippe (Denis & Schiffermuller, 1775) 32

Holly Blue Celastrina argiolus (Linnaeus, 1758) 25

Large Blue Phengaris arion (Linnaeus, 1758) 26

Large Heath Coenonympha tullia (Muller, 1764) 39

Large Skipper Ochlodes sylvanus (Esper, 1777) 13

Large Tortoiseshell polychloros (Linnaeus, 1758) 30

Large White Pieris brassicae (Linnaeus, 1758) 17

Lulworth Skipper Thymelicus acteon (Rottemburg, 1775) 12

Marbled White Melanargia galathea (Linnaeus, 1758) 36

Marsh Fritillary Euphydryas aurinia (Rottemburg, 1775) 33

Meadow Brown Maniola jurtina (Linnaeus, 1758) 38

Mountain Ringlet Erebia epiphron (Knoch, 1783) 36

Northern Brown Argus Aricia artaxerxes (Fabricius, 1793) 23

53 APPENDICES

Page no. for Common name Scientific name Authority species account

Orange-tip Anthocharis cardamines (Linnaeus, 1758) 18

Painted Lady Vanessa cardui (Linnaeus, 1758) 29

Peacock Aglais io (Linnaeus, 1758) 30

Pearl-bordered Fritillary Boloria euphrosyne (Linnaeus, 1758) 31

Purple Emperor Apatura iris (Linnaeus, 1758) 27

Purple Hairstreak Favonius quercus (Linnaeus, 1758) 20

Red Admiral Vanessa atalanta (Linnaeus, 1758) 28

Ringlet Aphantopus hyperantus (Linnaeus, 1758) 39

Scotch Argus Erebia aethiops (Esper, 1777) 36

Silver-spotted Skipper (Linnaeus, 1758) 13

Silver-studded Blue Plebejus argus (Linnaeus, 1758) 22

Silver-washed Fritillary Argynnis paphia (Linnaeus, 1758) 33

Small Blue Cupido minimus (Fuessly, 1775) 22

Small Copper Lycaena phlaeas (Linnaeus, 1758) 21

Small Heath Coenonympha pamphilus (Linnaeus, 1758) 38

Small Pearl-bordered Fritillary Boloria selene (Denis & Schiffermuller, 1775) 31

Small Skipper Thymelicus sylvestris (Poda, 1761) 11

Small Tortoiseshell Aglais urticae (Linnaeus, 1758) 29

Small White Pieris rapae (Linnaeus, 1758) 17

Speckled Wood Pararge aegeria (Linnaeus, 1758) 35

Swallowtail Papilio machaon (Linnaeus, 1758) 15

Wall Brown Lasiommata megera (Linnaeus, 1767) 35

White Admiral Limenitis camilla (Linnaeus, 1764) 27

White-letter Hairstreak Satyrium w-album (Knoch, 1782) 20

Wood White Leptidea sinapis (Linnaeus, 1758) 15

54 Acknowledgements

During the period covered by this report, the UKBMS project was co-funded by a multi-agency consortium led by the Department of the Environment, Food, and Rural Affairs and including the Countryside Council for Wales, Forestry Commission, Joint Nature Conservation Committee, Natural England, Northern Ireland Environment Agency, and Scottish Natural Heritage. The project is guided by a Steering Group which meets biannually and includes representatives from these organisations and from the volunteer recording community.

Although this funding support is essential to the existence and running of the UKBMS, without the contribution of an army of volunteers, it simply could not operate. We are indebted to all who co-ordinate and record butterfly transects throughout the United Kingdom, as well as to those who allow access to their land and in some cases actively promote butterfly monitoring thereon. The continued success of the UKBMS depends on a high level of volunteer support in order to provide the huge database on butterfly abundance throughout the UK. This data has immense value towards the preservation of our nation’s butterflies, enabling us to monitor the state of vulnerable species and sites, and to gain a better understanding of butterfly ecology. We will continue to try and give you the support and feedback you need and deserve.

We would like to thank the photographers for allowing their superb images to be used in this report.

Finally we would like to thank the Joint Reprographic Services (JRS) Unit - part of the support services to the UK Research Councils - for designing and printing the report

Butterfly Conservation is the charity aimed at securing a lasting future for butterflies, moths and their habitats. It works in partnership with thousands of volunteers and a wide range of organisations in the UK and to secure a healthy environment where we all can live.

The Centre for Ecology & Hydrology (CEH) is the UK’s Centre of Excellence for integrated research in terrestrial and freshwater ecosystems and their interaction with the atmosphere. As part of the Natural Environment Research Council (NERC) CEH works in partnership with the research community, policymakers, industry and society, to deliver world-class solutions to the most complex environmental challenges facing humankind.

The Department for Environment Food and Rural Affairs is the UK government department responsible for policy and regulations on the environment, food and rural affairs. The overarching challenge for Defra is to secure a healthy environment in which we and future generations can prosper. As we build a low carbon, resource efficient economy, Defra helps people to adapt to changes, deals with environmental risks and makes the most of the opportunity we have to secure a sustainable society and a healthy environment.

The Joint Nature Conservation Committee (JNCC) is the statutory adviser to Government on UK and international nature conservation. Its work contributes to maintaining and enriching biological diversity, conserving geological features and sustaining natural systems. JNCC delivers the UK and international responsibilities of the four country nature conservation agencies - Council for Nature Conservation and the Countryside, the Countryside Council for Wales, Natural England and Scottish Natural Heritage.

Natural England is an independent public body whose purpose is to protect and improve England’s natural environment, for its intrinsic value, the wellbeing and enjoyment of people and the economic prosperity that it brings.

Scottish Natural Heritage is the government body that looks after all of Scotland’s nature and landscapes, across all of Scotland, for everyone.

The Countryside Council for Wales is the Government's statutory advisor on sustaining natural beauty, wildlife and the opportunity for outdoor enjoyment in Wales and its inshore waters. It champions the environment and landscapes of Wales and its coastal waters as sources of natural and cultural riches, as a foundation for economic and social activity, and as a place for leisure and learning opportunities.

The Northern Ireland Environment Agency takes the lead in advising on, and in implementing, the Government’s environmental policy and strategy in Northern Ireland. It aims to protect and conserve Northern Ireland's natural heritage and built environment, control pollution, and promote the wider appreciation of the environment and best environmental practices.

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